Sequential interpenetrating polymer network confines shear-aligned graphene oxide liquid crystals enabling precise molecular sieving

Sequential interpenetrating polymer network confines shear-aligned graphene oxide liquid crystals enabling precise molecular sieving | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Sequential interpenetrating polymer network confines shear-aligned graphene oxide liquid crystals enabling precise molecular sieving Suryasarathi Bose, Ria Sen Gupta, Sk Safikul Islam, Dhondi Pradeep, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4381911/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Graphene oxide (GO)-based membranes hold great promise for revolutionizing nanofiltration, thanks to their seamless water transport and efficient ion and molecular sieving capabilities. However, challenges such as membrane disintegration under high pressure and nanochannel swelling due to water intercalation hinder their upscaling. In this study, we addressed these issues by aligning GO-based liquid crystals through shear forces and stabilizing their stacking using a sequential interpenetrating polymeric network (IPN) via electrostatic anchorage. This approach retained long-range order through nanoconfinement. By carefully selecting starting materials for the IPN, such as dopamine and GO liquid crystals, we achieved a nematic phase at extremely low concentrations, a feat not achievable with conventional methods. The resulting membranes were extensively characterized using microscopic and spectroscopic techniques, revealing pore sizes in the range of 7 nm facilitated by nanomaterial inclusion. These highly ordered and structurally robust membranes exhibited exceptional water flux (145 LMH) and long-term separation efficiency (> 97%) for monovalent and divalent salts, dyes, and antibiotics. Molecular dynamics simulations provided detailed insights into the ionic sieving mechanism of the GO-based IPN membranes. The MD simulations support that the water flux is reduced upon arresting the rGO-I sheets within IPN which scales with the concentration of rGO-I. In addition, this confinement at molecular length scales leads to a reduction in the number of ions residing within the membrane region, favouring retention within the feed region. These results well corroborate with the observed experimental evidence. Moreover, the membranes showed antifouling, chlorine tolerance, antibacterial properties, and cytocompatibility. They remained stable over repeated operational periods and endured a wide range of harsh environmental conditions without swelling. These resilient and robust membranes pave the way for large-scale membrane fabrication and sustainable water treatment. Scientific community and society/Water resources Physical sciences/Energy science and technology Liquid crystals sequential IPN mixed matrix membranes antifouling antibacterial non-cytotoxic salt rejection nanofiltration dye removal antibiotic removal Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1. INTRODUCTION Depletion of freshwater aquifers has continued to pose significant challenges for the global population, and thus purification of the existing water resources, including brine, brackish water, wastewater, and seawater, has become the focus of recent 1 research developments. 2,3 Membrane technology, being one of the most facile and effective separation techniques, represents a promising solution to gain considerable respite in this direction. New membrane materials coupled with easily scalable synthetic pathways are in heavy demand to overcome the roadblocks set by the current state-of-the-art RO membranes. 4 Disintegration upon exposure to harsh chemical environments and biofouling contribute majorly to the impairment and ultimate failure of commercial membranes. Two-dimensional (2D) nanomaterials have gained immense popularity in terms of mitigating fouling issues and enabling high-throughput and high-selectivity membranes. 5–7 In this regard, graphene oxide (GO), the “next-generation wonder material,” has gained prominence in research efforts and offers exceptional potential in separation applications. 8 High hydrophilicity, tuneable functionality, mechanical integrity, and flexibility provide ample opportunities for efficient ion and molecular sieving mechanisms. 9–11 However, disintegration under high operating transmembrane pressure and swelling of the nanochannels due to water intercalation have been reported to be the major engineering roadblocks in GO membrane upscaling. Efforts for controlling the swelling phenomenon have been mainly directed toward crosslinking and chemical reduction, which in general comes with challenges such as cytocompatibility, 11,12 Additionally, free-standing GO membranes are prone to corrugation via oxygen-containing moieties and hence need to be protected via embedding in a suitable polymeric matrix. 13 However, owing to compatibility issues between neat GO and the matrix arising from mismatched surface energies and aggregation of GO sheets, phase separation is evident, leading to deterioration of the desired properties. In this light, chemical modification of GO sheets is inevitable to enable miscibility. A mild and partial reduction of GO (with reduced interlayer spacing), coupled with appropriate functionality can solve the issues mentioned above. 14,15 Although GO membranes have been extensively explored in the recent past for their separation performance, a comparatively new research direction is the fabrication of GO-based lyotropic liquid crystalline materials. 16–22 These self-assembled highly ordered GO-based stacked structures exhibit superior mechanical properties owing to the presence of stable secondary interactions and have thermodynamically defined and characteristic length-scale domains, which aid in striking a perfect balance between permeability and specific selectivity. So far, free-standing GO liquid crystalline (LC) membranes have been reported in the literature with insignificant rejection efficiencies and requiring high concentrations of material for rendering LC phases. 23 In our previous work, a reactive liquid crystal GO-based monomer was explored which upon ultraviolet (UV) crosslinking resulted in a robust and chlorine-tolerant lyotropic LC membrane with promising separation efficiencies. 1 However, these high-performance free-standing membrane modules require external stimulus (UV, magnetic stirring, shearing, etc.) for demonstration of oriented structures and just like neat free-standing GO can undergo corrugation and suffer from brittle fracture under operating conditions. As a comprehensive remedy, which is usually not realizable using the conventional approaches discussed above, a membrane incorporating partially reduced and functionalized GO LC sheets with a sequential interpenetrating polymeric network (IPN) can offer a quantum leap of advancement in terms of the desired membrane properties. Accordingly, in this work, we report for the first time the engineering amalgamation of functionalized GO LC sheets and an IPN membrane derived from polyvinylidene fluoride (PVDF) and mussel-inspired dopamine. 2-Isocyanate ethyl methacrylate functionalized GO sheets were reduced via a mild and green reducing agent (green tea leaves). This functionalization helped in bringing down the interlayer-spacing of the neat GO sheets from 8 to 6 Å. Additionally, the functionalized reduced GO (rGO-I) sheets were able to demonstrate ordered nematic phases at much lower concentration than those reported in the literature and augmented the compatibility with the polymeric matrix. The IPN on the other hand, was instrumental in triggering the orientation and arresting the LC sheets inside the matrix without the need for any external stimulus and protected the rGO-I sheets from getting corrugated or delaminated besides maintaining the stacking periodicity, even after continuous exposure to aqueous environments. Fundamentally, the integration of the LC sheets and the sequential IPN membrane was actuated by anchoring the rGO-I sheets with the dopamine monomer prior to polymerization via electrostatic assembly. Subsequently, upon in-situ sequential polymerization and membrane fabrication, the rGO-I sheets were aligned and arrested at nanoconfined length scales that are required for precise molecular separation. Apart from electrostatic forces, the secondary interactions, such as dipole-dipole and π-π interactions between the dopamine moieties and the rGO-I sheets reinforced the interlayer bonding and helped in shaping the macroscopic stability of the LC membranes. The presence of the IPN helped in manipulating the LC phase to produce long-range order via nanoconfinement and the final membranes exhibit similar transitions described by Onsager’s hard-plate theory. 24 We show that the rGO-I@IPN_LC dope solutions show LC behavior and exhibit nematic phases as corroborated via rheological evaluations and small-angle X-ray scattering (SAXS) measurements. On the other hand, after fabrication of shear-aligned rGO-I@IPN_LC, the membranes retained their nematic LC phases with the existence of new lamellar phases, which is also evident from the SAXS. Additionally, the presence of zwitterionic polydopamine in the IPN matrix helped in regulating the surface charge of the membrane which further aided separation efficacy. The membranes were found to be extremely stable in terms of ion and molecular sieving efficacy and demonstrated high water flux (145 LMH, i.e., Lm − 2 h − 1 ). They were resistant to chlorine attack, were cytocompatible, had antibacterial properties, and exhibited excellent mechanical integrity at high transmembrane pressure. All-atom molecular dynamics simulations were utilized to investigate the permeation of water and the rejection of ions, offering intricate insights into the molecular mechanisms underlying ionic sieving facilitated by IPN membranes incorporating GO-LC. The adoption of such a hybrid mesophase route helped in achieving such robust membranes and paved the way for the potential designing of robust and sustainable GO-based LC membranes for water purification applications. Figure 1 demonstrates the salient features of the fabricated membrane. The rGO-I@IPN_LC dope solution demonstrated the presence of a nematic phase. The ordered phases (nematic and lamellar) were retained post IPN evolution, wherein IPN architecture not only helped in retaining the LC phase but also arrested swelling of the rGO-I sheets. 2. RESULTS AND DISCUSSION Designer LC membranes with long-range periodicity : The rGO-I LC was designed by partial and mild reduction of the GO-I sheets and was then added to the IPN dope solution consisting of PVDF and dopamine. The negatively charged rGO-I LC particles got electrostatically bound to dopamine owing to strong attractive forces between the two counter-charged species. Consequently, polymerization of the rGO-I-anchored dopamine occurred and led to long-range ordering of rGO-I LC sheets. The changes in the chemical environment brought about by the LC phase was probed via FTIR analysis shown in Fig. 2 a. The fabricated rGO-I LC sheets retained the characteristic peaks of neat GO (observed at 3200, 1721, 1612, and 1044 cm − 1 corresponding to hydroxyl -OH, carbonyl -C = O, C = C, and C-O stretching, respectively) and additionally showed two new peaks at 1295 and 1167 cm − 1 for the stretching vibrations of amide C-O and C-N. This is due to the successful reaction with 2-isocyanatoethyl methacrylate. However, the intensity of the oxygen containing peaks 25 such as -OH, -C = O, and C-O decreased owing to the mild reduction reaction with green tea. Additionally, the absence of any isocyanate peaks (~ 2275 − 2263 cm − 1 ) supplemented the successful covalent interaction with 2-isocyanatoethyl methacrylate. Upon the inclusion of the rGO-I sheets into the IPN, new peaks arising from the components of the matrix appeared. The new peaks could be ascribed to the strong -CH 2 bending and -CF 2 stretching of PVDF (1402 and 1167 cm − 1 , respectively), including a broad hump around 3369 cm − 1 from the -OH and -NH stretching of the polydopamine catecholamines, and two peaks centred around 1630 − 1548 cm − 1 from the scissoring as well as bending vibrations of N-H bonds. 26 The overlapping peaks and slight peak shifting in the final membrane further indicated the successful electrostatic inclusion of the rGO-I sheets and their interaction with the IPN network. Findings from the XPS spectra (Fig. 2 b) further strengthened the FTIR evaluations and shed light onto the intrinsic binding energies which characterized the strong electrostatic and capping interaction 27 of the LC sheets with the designer IPN membrane. The studies mainly indicated the presence of carbon, nitrogen, oxygen, and fluorine. The main difference between the GO sheets and the rGO-I LC sheets lie in the fact that the O 1s intensity decreased slightly as compared to neat GO owing to the mild reduction process. The amide bond present in rGO-I sheets is characterised by a peak of N 1s at 400.4 eV seen in the deconvoluted spectra. Upon deconvoluting the C 1s core spectra for rGO-I sheets ( Fig. S1 e ), three peaks were obtained around 284.68, 286, and 288.65 eV, corresponding to the presence of sp 2 /sp 3 hybridised carbon, carbonyl C-O, and O-C = O bonds, respectively. Also, the core C 1s spectra for the rGO-I@IPN_LC ( Fig. S1 a ) membrane along with the peaks mentioned above showed additional peaks at ~ 290.84 eV for the -CF 2 bond, 288.34 eV for O-C = O bonds, 285.75 eV C-O bonds, and 284.70 eV for sp2/sp3 hybridised carbon. 28 The presence of C-N bonds corroborated the interaction between the rGO-I sheets and the dopamine moieties. Another notable difference between the rGO-I sheets and the rGO-I@IPN_LC membrane was the fact that the IPN membrane had a strong presence of F 1s coming from the PVDF component which was absent in the neat rGO-I sheets. The presence of a peak at 532.55 eV in the deconvoluted O 1s spectra further substantiated the presence of oxygen on the surface of the membranes. No peak shifting was observed after dye removal experiments, which further stressed upon the reusability of the system. Only minor reduction in peak intensities were observed which could be attributed to interaction with the dye molecules. The effect of 2-isocynatoethyl methacrylate (ICM) incorporation on the interlayer distance of rGO-I compounds was evaluated by XRD (Fig. 2 c). The GO sheets exhibited an intense peak at 9.94°, corresponding to the (001) plane, with an interlayer distance of 0.89 nm. Upon reacting the modified GO-I sheets using “green tea extract”, a limited reduction was observed in the oxygenated functional groups, which led to the appearance of a 2-theta peak at 14.36°, indicating the formation of crystalline yet partially reduced rGO sheets with an interlayer distance of 0.62 nm. The fresh peak (weak) at 30.68° (0.29 nm) hinted at the presence of reduced GO-I nanosheets. 29 The IPN membrane exhibited a peak at around 20.56º due to the semi-crystalline nature of PVDF. 30 Finally, in the case of rGO-I@IPN_LC membranes, peaks corresponding to both rGO-I and IPN were present, indicating the successful insertion of partially rGO-I into the IPN matrix. The IPN matrix triggered the orientation of the LC sheets and also retained the interlayer-spacing of the LC sheets. In addition, we assessed the interlayer spacing of dry and wet rGO-I@IPN_LC membranes. However, the XRD spectra demonstrated no change in the interlayer-spacing of the membranes even after being dipped in water for a period of 90 days. This observation further supported the stability of the rGO-I@LC membranes which neither leached nor delaminated upon elongated periods of exposure to aqueous environments ( Fig. S2 ). The thermal profile and the mechanical integrity of the synthesized sheets and the membranes was evaluated from thermogravimetric analysis (TGA) (Fig. 2 d) and dynamic mechanical analysis (DMA) (Fig. 2 e). As observed from the TGA profiles, the rGO-I sheets record a weight loss of nearly 3% before 100 ºC due to the presence of physisorbed water molecules. The significant weight loss in the range 200–250 ºC and weaker loss in the range 250–800 ºC can be attributed to the degradation of less stable (CO, CO 2 , and H 2 O) moieties and stable oxygenated groups. However when compared to neat GO, 31 the rGO-I sheets exhibit greater stability due to stronger van der Waals interactions between the sheets owing to the mild reduction in the oxygen containing functional groups. Upon successful tagging of the rGO-I sheets with the IPN, the thermal behaviour becomes similar to that of neat IPN, 32 however the Tmax (temperature for the onset of maximum degradation) increased by 20–30 ºC. The tagging enabled an inclusion of 20% of the rGO-I sheets into the IPN matrix. We can thus draw an inference that the LC sheet inclusion aided the thermal property of the membrane and did not impair its thermal stability. A comparative DMA study was performed to gauge the effectiveness of the rGO-I LC sheet inclusion inside the IPN in terms of mechanical robustness. From the storage modulus versus temperature plots, it was observed that the presence of the sheets increased the storage modulus of the neat IPN membranes from 140 MPa to nearly 200 MPa. This increment can be mainly ascribed to the presence of the oriented LC sheets. Evolution of the morphology and surface properties in the rGO-I@IPN_LC membrane : Morphological evolutions were captured via a FESEM equipped with an EDX detector. The micrographs helped in providing a holistic understanding pertaining to the pore size reduction pathways. Here, the relatively large rGO-I (lateral dimension = 1250 nm) ( Fig. S3 ) sheets get anchored to the dopamine monomers via electrostatic interaction and when this anchored dopamine polymerizes via auto-oxidative polymerization, a dense network of polydopamine (PDA) aligned the rGO-I LC sheets and arrested swelling. The simultaneous diffusion of the rGO-I-anchored dopamine monomer followed by the nucleation and growth of polydopamine into the hydrophobic pore channels of PVDF ensured and further strengthened the pore size reduction mechanism. 33 Nonsolvent-induced phase separation (NIPS) cast membranes are characterized by a smooth surfaces, few nodules and the cross-section is populated with finger-like macro voids which arises owing to the quick phase inversion process and rapid exchange of solvent-nonsolvent in the coagulation bath. 34–36 However, after formation of an IPN, the surface is completely covered by the PDA and the surface roughness (more hydrophilicity) and asymmetry increases which is evident from the contact angle values (Fig. 4 c). The cross-section on the other hand for neat IPN membrane marks the presence of entangled networks and completely suppresses the finger and sponge-like morphology, which is a qualitative feature of IPNs. 37 The formation of the successful interpenetrated structure is also hinted upon by the suppression of macroscopic phase separation, an intrinsic property of IPNs. In the micrographs of the rGO-I LC sheets, ultrathin, wrinkled structures with distinct edges were observed, which is quite similar to rGO sheets reported in literature. 38 Upon their incorporation into the matrix, the surface features seem to change drastically. The rGO-I@IPN_LC membrane is characterized by increased surface roughness due to the rGO-I inclusions. When estimated via ImageJ software, it was observed that the pore sizes of the rGO-I@IPN_LC membrane reduced significantly to ~ 7 nm as compared to 300–500 nm for the neat IPN membrane. The obtained pore sizes were analogous to the data obtained from MWCO and BET analysis ( Fig. S5 ) and could effectively serve as nanofiltration membranes. The presence of the rGO-I LC sheets did not hamper the interconnected structure of the IPN membrane, and this was evidenced from the cross-section image of the rGO-I@IPN_LC membrane. The dense skin layer (40 µm) and the interconnected networks of the polymeric chains facilitate water transport but at the same time, the presence of the large sheets work in tandem to restrict the passage of the ionic species. 39 EDAX spectra revealed the elemental composition of the neat IPN (Fig. 3 e ) and the rGO-I@IPN_LC (Fig. 3 h ) membranes. The substantial increment in the elemental intensities of C, N, and O further corroborated the successful integration of the rGO-I LC sheets into the IPN architecture. We additionally investigated the EDAX spectra of the membranes after MB and CR dye rejection ( Fig. S11a,b ). Diametrically opposite observations were obtained for the oppositely charged dyes. Although elemental footprint of the MB dye molecules were captured in the spectra, the footprint for the CR dyes was strategically absent, which further substantiates the dye rejection mechanism described in detail in the performance section. The surface of the membranes was further evaluated using nitrogen adsorption-desorption experiments at 77.35 K ( Fig. S5 ). The average pore diameter or mean pore size was the metric that was calculated from the isotherms. The isotherm corresponded to the type IV pattern according to IUPAC nomenclature with a characteristic hysteresis loop appearing in the multilayer range. The shape of the hysteresis loop was most likely caused by capillary condensation in the mesoporous structures. The incorporation of the rGO-I was expected to result in a decrease in pore size. The average pore diameter of the rGO-I@IPN_LC membrane was found to be around ca. 6.96 nm. 40,41 The porous rGO-I@IPN_LC membrane with π-conjugated skeletons, impressive pore size, and permanent porosity is deemed to pave the pathway for the construction of next-generation membranes for molecular sieving. To supplement the pore size measurements obtained from BET measurements, MWCO analysis (Fig. 4 a) was performed using a range of neutral solutes (molecular weight ranging from 300–1400 Da). In brief, 10 ppm solutions of the neutral solutes were taken and their rejection efficiencies were evaluated using Eq. (4). From the studies it was observed that the membranes could reject 73% of Giemsa stain, 80% of Sudan IV, 85% of tetracycline, 89% of oxytetracycline, 98% of azithromycin and 99% of vitamin B 12 . The rejection of these neutral solutes were solely based on the pore sizes and from the rejection studies it can be roughly concluded that the MWCO of the membranes lie in the range of 450–1400 Da and hence the membranes are ought to have a pore size in the range of nearly 7 nm, which further supports the BET results obtained before. Apart from the features mentioned above, surface properties and charge play a major role in determining the end-use application of the membrane and also its intrinsic properties. Hydrophilic membranes are characterised by the heavy adsorption of water molecules on its surface thus generating a thick hydration layer which is essential for eliminating fouling issues. Thus, the evaluation of membrane nature is crucial in deciding its fate for long-term operation. With the help of a contact angle goniometer and deploying the sessile drop method, the water contact angle (WCA) values were studied which can be directly correlated to surface hydrophilicity/hydrophobicity via Young’s equation. 42 The rGO-I@IPN_LC membranes (Fig. 4 c) were found to exhibit a WCA value of 48º which was nearly 18º lesser than that of neat IPN. The significant enhancement in the hydrophilicity of the membranes can be attributed to the introduction of larger amounts of hydrophilic -OH and -NH and polar -C = O groups into the membrane backbone via integration of the rGO-I sheets into the IPN matrix. The hydrophilicity measurements from WCA values were further ascertained from the water uptake measurements. The uptake for the rGO-I@IPN_LC membranes was found to be nearly about 98%, which was 13% higher than that for neat IPN. 32 Also the roughness of the membrane surface increased owing to the LC sheet inclusion, which could be observed from the AFM images (Fig. 7 ). The RMS (Sq) roughness increased from 114.3 nm for neat IPN (PVDF/PDA) to 258.3 nm for the rGO-I@IPN_LC membrane (Fig. 4 d,e). For the hydrophilic surface, with significant increment in roughness, the subsequent decrease in the WCA values establishes the validity of the Wenzel state, i.e., where the rough patches are fully filled with water, rather than the Cassie-Baxter state where the rough patches contain air. This increases surface wettability, thus directly impacting the ability of the membrane to form hydration layer and ward off unwanted foulants from its surface. 43 Surface charge, the second most important surface feature was evaluated using an Anton Paar Surpass Zeta Analyzer machine. The electrokinetic interactions occurring at the membrane-solute interface hint at the surface charge of the membranes which is calculated using the Helmholtz-Smoluchowski equation. 44 The zeta potential of the rGO-I dispersions was around − 30 mV owing to presence of polar hydroxyl, carboxyl, and secondary amines. Upon the impregnation of these sheets into the IPN matrix, the zeta potential of the rGO-I@IPN_LC membranes were found out to be around − 36 mV which was numerically nearly 16 mV more than that of neat IPN membrane. This significant rise can be ascribed to the increment in the polar groups from PVDF and polydopamine. However, when the membranes were triggered with basic pH, the zeta potential further rose to -42 mV giving rise to greater negative charge density on the surface. This phenomenon can be described by the zwitterionic nature of PDA whose isoelectric point is around 4. Upon shifting to a more basic pH, the -OH groups get converted to O − , thus generating negative charges on the surface and accounting invariably for the high surface charge (Fig. 4 b). 45 Thus, the presence of the rGO-I LC sheets augment the charge carrying capacity of the IPN membranes and creates a platform for successful charge based separation performance. Shear aligned rGO-I LC sheets arrested by IPN : The most direct evidence of the retainment of the LC phase behaviour in the fabricated rGO-I@IPN_LC membranes was obtained from polarized optical microscope (POM) images. This LC phase suggests that the rGO-I sheets were arranged with long-range periodicity. The phase morphology of the IPN casting dope solution containing a range of different concentrations of rGO-I sheets in DMF along with the other IPN constituents was studied and gauged using POM ( Fig. 5 ). DMF was chosen as the solvent since all the constituents (PVDF and dopamine) were compatible and soluble in DMF. The neat IPN dope solution (only PVDF and dopamine) in DMF without the rGO-I sheets did not show the presence of any birefringence, which indicated that the LC phase in the rGO-I@IPN dope dispersion was primarily due to the presence of rGO-I nanosheets. To evaluate the phase behaviour of rGO-I@IPN dope dispersions, the concentration of rGO-I was varied from 1–20 mg/mL ( Fig. 5 and S6 ). Prominent birefringence with bright and dark brushes were found only after the concentration of the nanosheets exceeded 5 mg/mL and 7.5 mg/mL of rGO-I. Membranes fabricated with lesser rGO-I sheet concentrations (such as 1 mg/mL, 2.5 mg/mL, and 3 mg/mL) had significantly less sheets to show long range periodicity and the obtained membranes were non-uniform in nature. Thus such low concentrations were not taken forward. Although rGO-I@IPN dope solutions did show nematic phase formation at a concentration of 5 mg/mL in DMF, and also demonstrated ordered alignments of the LC rGO-I sheets, yet the desalination performance (NaCl rejection = 40%) was not satisfactory. Additionally, on increasing the concentration of rGO-I sheets in the IPN dope solution beyond 10 mg/mL, prominent birefringence was obtained, however the casted membranes were somewhat brittle which sacrificed their easy processability, and hence they were shelved. With all these observations in mind, we went ahead with dope solutions containing 7 mg/mL concentration of rGO-I sheets for our membrane fabrication. In the chosen concentration, i.e., 7.5 mg/mL, prominent birefringence was observed, and the stability of the obtained rGO-I@IPN dope solution was found to be extremely stable. Thus, the DMF containing dope solution of rGO-I@IPN with 7.5 mg/mL sheet concentration was taken forward and the exhibited well-recognized birefringence between the polarizers was direct evidence of the formation of lyotropic LC phase. Achieving such rGO-I LC would provide unique prospects for fabricating well-aligned, ordered, and novel rGO-I@IPN LC-based mixed matrix membranes. To further the understanding of the LC phase formation and study the structural improvements obtained via formation of the ordered phases, Small-Angle X-Ray Scattering (SAXS) was performed (Fig. 6 a,b). Precisely, the scattering factor ranges, q (q = 2π/d = 4π sin θ/λ) were employed to evaluate the structural advancements of rGO-I dispersions and the rGO-I@IPN_LC membrane. The required information pertaining to the structure of the rGO-I dispersion and the rGO-I@IPN_LC membrane was obtained from the Lorentz Correction Kratky plot (I*q 2 vs. q). From the Kratky plots at the chosen concentration of 7.5 mg/mL of the rGO-I sheets, crystal clear diffusive patterns and broad range scattering peaks were obtained at q nem = 0.056 and 0.074 Å −1 , which suggested the presence of a high-order nematic phase. After confirmation of the nematic phase in the dispersion, the SAXS experiment was repeated for the rGO-I@IPN_LC membrane, and the scattering image ( Fig. S7 ) was reported. From the scattering image, less intense broad peaks were detected at 0.42 Å −1 and 0.50 Å −1 , which further ascertained the retainment of the nematic phase of rGO-I in the final membrane. Along with the nematic phases, the shear alignment achieved while casting the rGO-I@IPN_LC membrane, led to the appearance of two additional peaks near 0.106 Å −1 and 0.116 Å −1 indicating the existence of lamellar phase. Thus, it can be rightfully concluded that the presence of the high-order nematic and lamellar phases in the rGO-I@IPN_LC membrane was only due to the addition of the rGO-I nanosheets and IPN further arrested this phase in the membrane. 46,47 Now, to identify the viscoelastic phase behaviour of the rGO-I@IPN dope solutions rheological studies were performed which were very crucial in this study. Figure 6 c displays the variation of complex viscosity as a function of shear rate for different concentrations of rGO-I nanosheets in the IPN dope solution. In general, is it the behaviour of the fluid that decides its nature (i.e. Newtonian and non-Newtonian (shear thinning)). Here, the concentration of the rGO-I (ϕ) nanosheets played a major role in deciding the nature and the behaviour of the dope solution. From the plot, a pseudoplastic shear-thinning behaviour was obtained at various concentrations of the rGO-I nanosheets. The reduced complex viscosity of the rGO-I@IPN solutions with increased shear rates was in accordance with earlier reports. At low shear rates, the nematic phases in the GO-ICM@IPN dispersion were seen to be distributed randomly and they did not align, which resulted in higher viscosity. However, at high shear rates, the randomly distributed rGO-I sheets, demonstrating nematic phases were found to perfectly align in the direction of shear stress. This in turn produced less physical interaction and thus decreased the complex viscosity. The viscosity of rGO-I@IPN solutions depended on the rGO-I content and molecular arrangements. Figure 6 d shows the plot of zero shear viscosity as a function of rGO-I concentration (ϕ) at shear rates of 0.1 s − 1 . At a low concentration (ϕ = 0.25 mg/mL), rGO-I@IPN dispersion in DMF was found to exhibit an isotropic phase post which the viscosity increased up to a specific concentration ϕ c ca. 1mg/mL and attained a maxima. Upon further increasing the rGO-I concentration in the IPN dope solution a steady decrement in the complex viscosity was obtained which reached a minima and subsequently started increasing. A probable explanation for the decline in zero shear viscosity could be due to the formation of a less-viscous nematic liquid crystalline phase of rGO-I. The isotropic to the nematic phase transition was observed when the rGO-I nanosheet content in the IPN dope solution ranged between maxima and minima, while in zero shear viscosity condition. An isotropic to nematic phase change was observed at a concentration range from 1-2.5 mg/mL. Herein, ordered nematic phase was obtained after ϕ c reached the concentration of 2.5mg/mL of rGO-I nanosheets in the IPN dope solution. The complex viscosity of the rGO-I@IPN dope solutions were found to exhibit decent agreement with the viscosity power law model in Fig. 6 c. Usually, the exponents for ideal plastic material is about − 1 (power law model), which reduced from − 0.4165 to − 0.6898 by increasing rGO-I concentration from 0.25 to 7.5 mg mL − 1 , confirming the enhanced plasticity originating from the order nematic rGO-I phases. 23,48,49 Water transport properties and dynamic antifouling studies A thin, robust, and selective membrane is supposed to yield the most favourable filtration performance. The presence of liquid-crystal rGO-I nanomaterials soldered inside the IPN membrane matrix, creates a platform for the fabrication of promising systems enabled with enhanced water permeation and superior rejection properties. Evaluation of pure water flux is an important criterion for water remediation systems since it is very difficult to hit the age-old trade-off between selectivity and permittivity of membranes. The pure water flux values were evaluated in the pressure range of 10 to 100 psi ( Fig. S8 ). The rGO-I@IPN_LC membranes exhibited linearity in the flux values upon steady increment in the transmembrane pressure (85 LMH at 25 psi, 105 LMH at 50 psi, 120 LMH at 75 psi, and 145 LMH at 100 psi). The flux values fall within the range of ultrafiltration to nanofiltration range. This linear increment is probably due to changes in pore architecture which is often brought about by the variation in transmembrane pressure. Additionally, the data is in accordance with the Hagen–Poiseuille (HP) model for laminar membranes. However, when compared to the neat IPN membranes (900 LMH at 50 psi), the rGO-I@IPN_LC membranes showcase a much lower flux value which can be due to the pore tightening feature brought about by the large aspect ratio rGO-I sheets inside the IPN matrix. These sheets fill in the pore volumes and result in effective pore size reduction. The distribution of the sheets is facilitated by the fact that the rGO-I sheets are electrostatically bound to the dopamine moieties of the IPN membrane which upon sequential in-situ polymerization makes these sheets available to the system. Additionally, the enhanced water permeation of the fabricated membranes can also be attributed to the presence of the functionalized and partially reduced GO sheets (i.e. rGO-I sheets) where there is an inherent reduction in the density of oxygen containing moieties (as compared to neat GO) which in turn helps in frictionless water transport via slip flow mechanism through the ordered channels of the rGO-I sheets present inside the IPN matrix. 50 The water transport via these membranes is effectively due to a combination of pores and narrowed nano channels of the aligned rGO-I LC sheets. The flux experiments were continued for a period of 3 weeks for testing the long-term stability of the fabricated membranes under high transmembrane pressure (Fig. 7 a). It was observed that the change in flux values throughout the duration of the operation was quite negligible, thus establishing the long-term stable performance of the membrane. FTIR and XPS studies ( Fig S9, S10 ) were also performed to check the effect of such long-term performance on the inherent environment of the membrane. No change was observed in the chemical environment and functionalities of the membrane. After completion of the pure water flux experiments, the pure water feed was replaced by a feed solution of Bovine Serum Albumin (BSA) for gauging the antifouling abilities of the synthesized membranes (Fig. 7 b). For a membrane to qualify as antifouling, the membrane surface after being exposed to a bio foulant (here BSA) should quickly recover its initial performance after getting rid of the foulant via backflushing. Thus the flux recovery or retention should be very high for asserting its fouling-resistant nature. It was observed that the flux recovery ratio of the rGO-I@IPN_LC membranes was nearly 98%, which is much higher than the neat IPN membranes (85%). 51 In general, negatively charged membranes naturally repel co-charged foulants via electrostatic repulsion. The rGO-I@IPN_LC membranes being negatively charged (evidenced from the zeta potential values) are efficient enough to repel the BSA molecules from adhering onto the surface due to their high surface roughness and hydrophilicity. The high hydrophilicity subsequently leads to the formation of an impermeable hydration layer which further strengthens the repulsion of the BSA molecules. 52 Precise molecular sieving in IPN-arrested rGO-I LC sheets : The presence of positively charged Dopamine.HCl helped in binding the counter charged rGO-I sheets electrostatically to itself and upon sequential polymerization of dopamine-anchored rGO-I, a jammed network consisting of PVDF, and liquid crystal rGO-I anchored PDA (polydopamine) was obtained. Thus, the existence of the IPN was instrumental towards further triggering and arresting the alignment of the rGO-I LC sheets and also helped in controlling the d-spacing of the sheets (~ 6 Å) without the need of external crosslinking. The effectiveness of such a IPN aligned structure can be understood from the ion transport properties of the membrane. With reasonably high water flux values, the membranes (rGO-I@IPN_LC[ 1 ] and rGO-I@IPN_LC[7.5]) were subjected to salt rejection studies. 2000 ppm of monovalent (NaCl) and divalent (Na 2 SO 4 and MgSO 4 ) salts were taken as feed and the removal efficiency was evaluated at regular intervals using a TDS meter (Fig. 7 c). The membranes with 7.5 mg/mL concentration of rGO-I sheets, rejected nearly 97% of NaCl for a continuous period of 21 days after which the percent rejection decreased negligibly (~ 95.6%). The negatively charged membrane surface and pores can effectively repel the co-charged Cl − ions and the rejection of the Na + can be explained from the cation-π interactions occurring between the monovalent ion and the sp 2 hybridised structures of rGO-I sheets. 16,53 After a period of 21 days it was observed that the zeta potential of the membranes reduced a bit (initial value = -36 mV, after 21 days of NaCl rejection = -33 mV) and the EDAX spectra of membrane hinted at the presence of Na + ions ( Fig. S11c ), which could further explain the insignificant decrement in salt rejection incurred after 3 weeks of continuous operational cycles. However, the membrane with no LC phase, i.e. the membrane with 1 mg/mL of rGO-I sheets were found to reject only 25% of NaCl salt. This observation strengthens the fact that the formation of LC phases contributes greatly to effective ion rejection owing to the highly oriented architecture and thus justifies the rationale behind taking forward only the membrane with 7.5 mg/mL concentration for further studies. The salt removal efficiencies were also tested with divalent salts (Fig. 7 d) and it was observed that for both Na 2 SO 4 and MgSO 4 , the rejection efficacy reached nearly 99% owing to the larger hydrodynamic radii of the concerned ions. Intrinsically speaking, high-valence SO 4 2− undergoes greater repulsion via the membrane surface and pores than Cl-, while low-valence Na + faces higher electrostatic attraction as compared to Mg 2+ . In general, a possible overall mechanism behind such rejection efficiencies stems from a host of factors including reduced pore size, narrowed d-spacing and strong electrostatic interactions (high negative charge on membrane surface from zeta potential values). In the rGO-I@IPN_LC membranes the negatively charged groups and the size-reduced pore walls retain the counter-charged ions and repel the co-ions via the Donnan exclusion principle and size sieving mechanisms. This is necessary in order to maintain charge neutrality on either side of the membrane. Besides, the ordered nanochannels with reduced interlayer-spacing of the rGO-I LC sheets present inside the matrix also augments the ion rejection efficiency. For further investigating and exploring the charge-based rejection ability of the LC membranes, the membrane surface charge was triggered by altering the pH of the membrane environment. PDA being zwitterionic in nature is deemed to be capable of varying the nature of surface charge based on pH. The membrane was thus endowed with negative charges with basic pH since the -OH groups present in the PDA structure are quantitatively much more in number than that of -NH, accounting for higher negative charge density. 32 After pH variation, the surface exhibited a negative charge density of -42mV and the NaCl rejection efficiency rose to 99.8% and the results remained consistent for the entire duration of 21 days (Fig. 7 d). This result corroborates the fact that more the surface charge density, more is the efficacy demonstrated towards resisting the monovalent ion transport. To further substantiate the ion and dye nanofiltration performance a host of cationic and anionic dyes and antibiotics were taken as model foulants. Separation mechanisms can have synergistic contributing factors including Donnan exclusion, size sieving mechanism (pore size and narrow interlayered channels), and complex formation. Intrinsic features such as surface charge, hydrophilicity of the surface and a range of other operational conditions also affect the removal performance. The presence of rGO-I LC sheets not only leads to pore size reduction owing to their aspect ratio but also provides negative charge carrying centres which augments the surface charge of the fabricated membranes. The membranes were able to reject nearly 97% of the anionic dye CR and the rejection improved to 99% for the cationic MB dye (Fig. 7 e). MB being cationic in nature experiences high electrostatic attraction to the negatively charged membrane and gets strongly adsorbed to the membrane surface (evidenced from its elemental footprint in EDAX spectra). The anionic dye on the other hand faces repulsion being co-charged and steric hindrance also accounts for its rejection. However, its elemental footprint is not exhibited in the EDAX spectra which further verifies the repulsion hypothesis. Mixture of dyes involving MB and CR were also taken for dye rejection studies. As evidenced from the UV-Vis spectra the signature peaks corresponding to the dyes were strategically absent in the membranes could be cleaned easily via backflushing and could reject nearly 15 cycles of the dyes with no significant deterioration in the rejection efficiency ( Fig. 12c,d,e ). The rejection performance was further corroborated using another set of cationic, Safranin O and an anionic, AB dye ( Fig. S12g ). Here too similar trends in rejection efficacy were obtained. Similar observations were made during antibiotic removal experiments. The negatively charged amoxicillin got heavily repulsed by the negatively charged membrane and recorded a rejection of about 97%. For the neutral azithromycin antibiotic, the reduced pores of the membrane and the narrowed interlayer spacing of the rGO-I LC sheets worked in tandem to yield a rejection percentage of 98% (Fig. 7 f). In order to gauge the performance and durability of the membranes, we investigated their chlorine tolerance properties. Most of the commercial membranes are attacked by the chlorine present in water which in turn deteriorates its intrinsic properties and separation performance. In brief, the membranes are exposed to strong concentrations of sodium hypochlorite solutions and are again subjected to NaCl rejection experiments. The lesser the deviation in the rejection values, more resistant is the designed membrane towards chlorine attack. The rGO-I@IPN_LC membranes demonstrated just a 3–5% reduction (Fig. 7 d) in the salt rejection values after being exposed to chlorine. In all probability, such superior chlorine tolerance arises from the fact that the free chlorines get trapped via the primary and secondary amines of polydopamine which in turn restricts amide formation. Thus, chlorine attack fails to impede the membrane performance or adversely affect its intrinsic architecture. The 3–5% decline results from the inevitable attacks made by the free chlorine atoms on the -NH groups of the rGO-I LC sheets. Risk assessment and antimicrobial properties : The antibacterial performance of the fabricated rGO-I@IPN_LC membranes was effectively gauged from the standard plate count method. Both S. aureus and E. coli were used as the model bacterial strains for carrying out the evaluations. In general, wastewater contaminated with bacterial microorganisms can pose serious health hazards upon entering the ecosystem. Thus, removing them from the wastewater resources poses to be a major research concern. For the fabricated membrane, a 3-log reduction (percent reduction ~ 99.8) was observed for the gram-positive bacterial strain, i.e., S. aureus , and a 2-log reduction (percent reduction ~ 99.54) was obtained for E. coli , the gram-negative strain. Figure 8 a,b demonstrates the digital images for both the bacterial colonies formed in the TSA plates in the neat IPN, the control samples, and rGO-I@IPN_LC membranes. Here the presence of the functionalized GO is primarily responsible for such superior bacterial response. GO is widely known for its antibacterial activities due to sharp edges 54 (which physically disrupts the cell membrane of the bacteria) and its ability to generate huge amounts of oxidative stress via apoptotic mechanisms. 55,56 The fabricated membrane is incorporated with partially reduced functionalized GO which did not hamper its lateral dimension and oxygen functional groups much (as evidenced from the AFM images ( Fig. S3 and FTIR spectra). Thus, these nanomaterials present in the IPN matrix were solely responsible for inhibiting bacterial growth based on the similar mechanisms mentioned above for GO. However, it was observed that the inhibition of bacterial growth was higher for S. aureus as compared to E. coli. A plausible mechanism for this observation lies in the fact that the synthesized nanoparticles, rGO-I being negatively charged strongly interferes with the bacterial lipid polysaccharide membrane of the positively charged S. aureus, thus producing significantly high amounts of H 2 O 2 which damages the S. aureus membrane. 57 However, E. coli possess negative lipopolysaccharides on its exterior and hence its permeability towards the rGO-I moieties is comparatively a bit lesser, which explains for its lesser log reduction. 58 In addition to the antibacterial performance, the membranes were also tested for in-vitro cyctotoxcity. This feature of the rGO-I@IPN_LC membranes were evaluated using the standard MTT assay protocol. In general, GO is cytotoxic in nature. Studies usually suggest that on reducing the lateral size of the sheets, cytotoxicity decreases. Here, L929 mammalian cell lines were subjected to this test evaluation. As per the test standards, cytotoxic potential of the evaluated material increases with decrease in cell viability as calculated from the optical density measurements. If the neat sample (i.e., 100% extract) has a cell viability of lesser than 70% then the material is deemed to be cytotoxic. However, the rGO-I@IPN_LC membrane exhibited a cell viability of nearly 73% for the 100% test sample and the viability increased linearly with decrease in the extract percentage, reaching a maximum of 90% for the 10% test sample (Fig. 8 c). Thus, the fabricated samples could be claimed as non-toxic or cytocompatible towards mammalian cells, which is an important prerogative for water remediation systems. Additionally, from the long-term leaching studies (UV-Vis spectroscopy of the water permeate generated after long-term operation, Fig. S12h ), it was found that the fabricated rGO-I sheets did not escape into the permeate. This non-leaching behaviour arises from the fact that the nanosheets are not exposed to the environment, rather the IPN matrix protects the rGO-I LC sheets inside its matrix and prevents any further leaching. This evidence further establishes the cytocompatible nature of the fabricated rGO-I@IPN-LC membranes. Fundamental understanding of the membrane performance using MD simulations We employed all-atomistic MD simulations to understand the mechanisms governing the superior separation performance of the rGO-I@IPN-LC membranes. The membranes studied include an IPN membrane comprising PVDF and polydopamine chains but without rGO-I, as well as two variations of the rGO-I@IPN membrane: rGO-I@IPN[ 4 ] with a lower rGO-I concentration (number of rGO-I layers considered 3) and rGO-I@IPN[7.5] with a higher rGO-I concentration(number of rGO-I layers considered 6). In the lattermost scenario, the rGO-I exhibits extensive ordering, indicative of LC behaviour with well-defined nematic phases having an interlayer spacing of 0.62 nm. A cartoon illustrated in Fig. 9 a describes schematically as to how the feed side saltwater solution and the permeate side freshwater solution are separated by the LC membrane. Figure 9 b shows the number of water molecules permeating through the different membranes (IPN, rGO-I@IPN[ 4 ], rGO-I@IPN[7.5]) as a function of simulation time under a feed-side pressure of 100 MPa for a NaCl salt solution. Therein, one can see that the number of water molecules permeated across the membrane scales linearly with time, implying that a roughly constant chemical potential and pressure gradient is maintained in the simulations over time. As seen in the experiments, the MD simulations support that the water flux is reduced upon impregnation of the IPN membrane with rGO-I, with a higher reduction in water permeability at a higher rGO-I concentration. A comparison of Fig. 9 b and Fig. 9 c shows that the water permeability is similar for NaCl and Na 2 SO 4 aqueous solution, indicating that the water transport occurs independently of ion transport. We also report the water permeance and salt rejection for NaCl and Na 2 SO 4 salt solutions with different membranes, in Fig. 9 d and Fig. 10 . The water permeability is defined as the volume of water permeated per unit time, membrane area, and pressure. Similarly, the percentage of salt rejection is defined as \(\left(1-\frac{\text{T}\text{o}\text{t}\text{a}\text{l} \text{n}\text{u}\text{m}\text{b}\text{e}\text{r} \text{o}\text{f} \text{i}\text{o}\text{n}\text{s} \text{i}\text{n} \text{p}\text{e}\text{r}\text{m}\text{e}\text{a}\text{t}\text{e} \text{s}\text{i}\text{d}\text{e} \text{a}\text{t} \text{t}\text{i}\text{m}\text{e} t}{\text{T}\text{o}\text{t}\text{a}\text{l} \text{n}\text{u}\text{m}\text{b}\text{e}\text{r} \text{o}\text{f} \text{i}\text{o}\text{n}\text{s} \text{i}\text{n} \text{f}\text{e}\text{e}\text{d} \text{s}\text{i}\text{d}\text{e} \text{a}\text{t} \text{t}\text{i}\text{m}\text{e} \text{t}=0 }\right)\times 100\) , where t is the simulation run time, and the total number of ions is defined as the sum of the numbers of positive and negative ions. Notably, as seen in Fig. 9 d the MD simulation results are within 25% of the experimental water permeance, which indicates that the proposed all-atomistic model of the membrane can capture the physics of water and ion transport, as well as the chemistry of the rGO-IPN membranes. Moreover, as seen in Fig. 10 , our simulations demonstrate a 100% salt rejection for NaCl and Na 2 SO 4 salt solutions, even after an 85 ns simulation period, wherein no ions are able to reach the permeate region. This remarkable result is attributed to the high barrier that impedes ion passage across the membranes. Figure 10 vividly illustrates that the majority of ions remain within the feed region, while a few do enter the membrane, although none of the Na + , Cl − , and SO 4 2− ions reach the permeate side. Furthermore, our simulations also reveal that an increase in the concentration of rGO-I sheets integrated within the IPN (PVDF and PDA chains) membranes leads to a reduction in the number of ions residing within the membrane region, favouring retention within the feed region. Interestingly, we found that chloride ions pass more frequently from the feed region to the membrane region compared to sodium ions for NaCl salt solution. This trend is clearly depicted in Fig. 10 , wherein, initially, the feed region contains 18 Na + and 18 Cl − ions for the NaCl salt solution, while for the Na 2 SO 4 salt solution, there are 16 Na + ions and 8 SO 4 2− ions maintaining the same molarity in both cases. Overall, our simulation framework develops a comprehensive model for rGO-I@IPN membranes and provides molecular-level insights into ion permeation and salt rejection via them. 3. DISCUSSION A GO sheet is characterized mainly by oxidized and non-oxidized domains and very scantly via holes. 59 The non-oxidized domains contribute to the formation of specific percolating regions and contribute to efficient water permeation and ion selectivity. Herein we establish partially reduced rGO-I sheets via feasible chemical interactions and form stable mixed matrix membranes where lyotropic liquid crystalline rGO-I sheets were electrostatically anchored to IPN matrix and the LC behaviour was retained even in the mixed matrix system. The electrostatic interactions, π-π interactions and the hydrogen bonds formed between the IPN, and the rGO-I sheets helped in further arresting the shear aligned rGO-I sheets. Thus, the membranes exhibited the existence of nematic phases. The retainment of LC behaviour effectively offers a pathway to long-range order and can be attributed to the orientational property of the LC sheets which was triggered by the nano confinement of IPN. 60–62 The IPN also helped in protecting the sheets from swelling and preserved their narrow interlayer spacing. Leaching of the nanosheets also gets restricted via the mixed matrix IPN strategy. 63 Such highly ordered membrane matrix shows stable water permeation and ion sieving for long operational periods and can be easily reused via backflushing with DI water over several operational cycles. Additionally, our comprehensive MD simulations reveal the mechanism of ion rejection by the rGO-I@IPN membranes to be the inability of most ions to enter the membranes and the the prevention of the ions that do enter to exit the membrane. 4. CONCLUSION A novel and lyotropic liquid crystal enabled IPN membrane was reported by in-situ electrostatic attachment of rGO-I LC sheets in a IPN polymeric matrix composed of PVDF and PDA. The rGO-I sheets were obtained via a facile, practicable, and mild green-tea reduction methodology. Interestingly the LC structure of the rGO-I sheets were maintained even after membrane fabrication which aided membrane stability and performance. The fabricated membranes were chemically, thermally and mechanically quite resilient, owing to the interpenetrated structure. The reported procedure offers the coalescence of several distinctive traits that are imperative for sustainable water remediation. The membranes were characterised by stable long-term water flux (145 LMH) under high transmembrane pressure, and enhanced separation performance in terms of dye (> 98%), salt (97%) and antibiotic (98%) rejection. The strong chlorine resistance and antifouling characteristics further demonstrated the usability of these membranes. The membranes also demonstrated quick bacterial reduction capabilities for both gram negative ( E. coli , 2-log reduction) and gram-positive ( S. aureus , 3-log reduction). The cytocompatible behaviour of the membranes against mammalian cell lines, place them in the safe category of risk assessment while being disposed of in a landfill. In general, the existing state-of-the-art RO membranes are devoid of bactericidal properties, essentially requires UV pre-treatment and prefiltration steps with an antiscalant in the feed for mitigating fouling. However, our mixed matrix IPN approach can mark the arrival of sustainable antiscalant free antifouling membranes for water remediation and has the potential for large scale deployment, thus providing sustainable and guaranteed water supply for the generations to come. 5. EXPERIMENTAL SECTION Materials and Methods : Polyvinylidene fluoride (PVDF (Kynar 761 grade, Mw = 440,000 g/mol) was obtained from Arkema. Graphene oxide (GO) was procured from Nanomatrix Materials (Rajasthan), India. Sigma Aldrich provided 2-isocynatoethyl methacrylate (ICM), dibutyltin dilaurate (DBTDL), N,N-methylene bisacrylamide, dopamine hydrochloride (DA, 99%), and sodium periodate (NaIO 4 , ≥ 99.8%). Tris(hydroxymethyl)aminomethane (Tris, 99.8–100%) was purchased from Sisco Research Laboratories Pvt. Ltd. N, N-dimethylformamide (DMF, 99.0%), dimethylacetamide (DMAc, 99%) sodium hypochlorite, and sodium hydroxide pellets (NaOH, 97.0%) were acquired from SD Fine Chemicals Ltd. Methylene blue (MB, 319.85 Da), Congo red (CR, 696.665 Da), amido black 10B (AB, 595.5 Da), safranin O (SO, 350.85 Da) dyes, green tea, and dry acetone were obtained from a local vendor. Giemsa stain (GS 291.8 Da), Sudan IV (SD 380.44 Da), tetracycline (TC 444.43 Da), oxytetracycline (OTC 460.46 Da), azithromycin (Azithro, 785 Da), amoxicillin (365.4 Da), and vitamin B 12 (VB 1355.37 Da) were obtained from SRL Chemicals. All the chemicals and obtained materials were used without further processing and purification. Synthesis of rGO-I : The obtained GO was modified 64 using 2-isocynatoethyl methacrylate kept in dry acetone in the presence of nitrogen atmosphere. In essence, GO was effectively dispersed in dry acetone and was bath sonicated for 30 minutes. Subsequently, 2-isocynatoethyl methacrylate was incorporated into the system dropwise. The reaction mixture was stirred for 24 hours at room temperature under a nitrogen atmosphere in presence of a DBTDL catalyst. Upon completion of 24 h, the product was washed and centrifuged using THF and was then vacuum dried at 60°C. The modified GO was termed GO-I . To reduce the GO-I particles obtained in the previous step, reduction was carried out using green tea extract. The extract was prepared using 2 g of market-available green tea. It was mixed with 50 mL of distilled water at 70°C for 30 min. The extract was obtained by isolating the tea leaves and was stored in the refrigerator for further use. For the reduction step, the extract (10 mL) was added dropwise to a 40 mL aqueous suspension of the modified GO (10 mg/mL) for 45 min. Subsequently, the mixture was refluxed for 6 h at 60°C. Finally, the product was isolated by centrifugation at 8000 rpm for 15 min. It was then washed with DI water four times and dried overnight in an oven at 70°C. The obtained product was termed as r GO-I . Fabrication of rGO-I LC-anchored IPN membrane : 30 wt% of membrane casting solution (dope solution) was prepared in DMF (7 mL) using PVDF and dopamine.HCl monomer in a 2:1 ratio. At an elevated temperature of about 80 º C, the components were stirred continuously until a consistent bubble-less solution was obtained. To this, different amounts of rGO-I (10 mg, 75 mg, and 200 mg) in DMF (3 mL) were added. The solution was stirred in a hot plate until a homogeneous and uniformly mixed dope solution (1 mg/mL, 7.5 mg/mL, and 20 mg/mL, respectively) was obtained. Subsequently, to realize the casting of the membranes, a 300 µm doctor blade was taken, and a speed of 7–8 cm/s was set in an automatic film applicator for casting the membranes onto a glass plate. The membranes were then precipitated in a cold (ca. 4 ºC) aqueous coagulation bath containing 10 mM of tris buffer (pH = 8.5) and 5 mM of NaIO 4 . The precipitated membranes were kept in the cold buffer solution for 7 days. This was done in accordance with previous optimized studies for maximum reduction in pore size. 32 The fabricated membranes were then thoroughly washed and rinsed with ultrapure water before any assessments were carried out. The fabricated membranes were termed rGO-I@IPN_LC ( rGO-I@IPN_LC [ 1 ], rGO-I@IPN_LC[7.5] , and rGO-I@IPN_LC [ 20 ]) membranes. The rGO-I@IPN_LC[ 20 ] membrane exhibited a very uneven surface and was scrambled up due to high dosage of gGO-I ; hence this particular concentration was not taken forward. The rGO-I@IPN_LC[ 1 ] membrane dope solution did not show the presence of any prominent birefringence (which is typical characterization of LC behaviour), and consequently, this membrane proved ineffective in achieving efficient rejection performance. Here, the rGO-I@IPN_LC membrane refers to the membrane with 7.5 mg/mL concentration of rGO-I sheets. Scheme 1 illustrates the chemical reaction involved during the synthesis of the rGO-I sheets and subsequently the design of the rGO-I@IPN_LC membrane. Scheme 1. Chemical reaction involved in the synthesis of rGO-I particles and subsequent fabrication of the rGO-I@IPN_LC membrane via the non-solvent induced phase separation technique. Synthesis of charge-triggered membranes via pH variation : Membrane charges were triggered by tuning the pH of the membrane environment. The fabricated membranes were dipped either in 1 N HCl or 1 M NaOH (depending upon the requirement) for a period of 24 hours at room temperature. Before using the membranes, they were washed thoroughly with DI water. Computational modelling and simulation details : We used classical molecular dynamics (MD) simulations to examine the desalination performance of the IPN-based GO LC membranes for two different salt solutions (i.e., NaCl and Na2SO4). The system consisted of the membrane, saltwater on the feed side, and freshwater on the permeate side, with a simulation box length of 24 nm in the z direction (perpendicular to the membrane) and a cross-sectional area of 5.2 × 5.2 nm2 in the xy plane (parallel to the membrane), as illustrated in Fig. 9 a. For the feed-side region of the simulation box, we included 5000 water molecules, 18 Na + ions, and 18 Cl- ions, resulting in a molar concentration of aqueous salt solution of 0.2 mol/L (~ 11.7 g/L). On the permeate (pure water) side, we added 3000 water molecules. We used the open-source GROningen MAchine for Chemical Simulations (GROMACS) package for carrying out the MD simulations. The simulation timestep was taken as 1 fs and simulations were run for ~ 90 ns. During the simulations, we employed a cutoff distance of 12.0 Å for the Lennard-Jones (LJ) interactions, while long-range electrostatic interactions were calculated using the Particle-Mesh-Ewald (PME) method. After setting up the simulation box, energy minimization was performed using the steepest descent method with a maximum step size of 0.01 Å and a force tolerance of 10 kJ mol − 1 nm − 1, and subsequently the system was brought to equilibrium in the canonical ensemble (maintained at constant NVT, where N represents the number of atoms, V the volume of the system, and T the absolute temperature of the reservoir), while maintaining the permeate and feed side pistons both at atmospheric pressure (1 atm) for 4 ns. To apply the desired pressure (1 atm) on the piston atoms, we froze the atoms in the piston group in x and y directions and then applied a constant force pulling on the centers of mass of both the pistons, containing 1008 atoms each (in opposite directions) with a total force equal to 1.68156 kJ/mol nm. During the simulations, the system was coupled to a global thermostat using Langevin dynamics with a damping factor of 5.0 ps-1. Finally, the non-equilibrium MD simulations were conducted using the NVT ensemble with a uniform pressure (P), i.e., 100 MPa, applied on the feed-side piston along the flow direction (+ z), while atmospheric pressure (1 atm) was applied to the permeate-side piston opposite to the flow direction (–z). Periodic boundary conditions were applied along all three directions (x, y, and z). The number of water molecules and ionic species moving from the feed to the permeate side were monitored over time to determine the water flux and the ion rejection. Construction and setup of the rGO-I@IPN_LC membrane and desalination system and details on the force-field parameters The appropriate selection of force-field parameters is essential for ensuring the accuracy of classical MD simulations. In this work, the LJ and Coulombic interatomic parameters provided by Zeron et al. were employed for the Na + , Cl − , and SO 4 2− ions 65 , while Cheng et al.’s parameters were used for the carbon atoms (only the LJ parameters as carbon atoms have no partial charges) 66 . Water molecules were represented using the four-site TIP4P/2005 model. 67 The all-atom optimized potentials for liquid simulations (OPLS/AA) force-field parameters were used for the atoms in the PVDF and PDA chains, as well as in the rGO-I sheets, as generated using PolyParGen. 68 The .gro files of PVDF with 6 monomeric units and PDA with 4 monomeric units were generated using PolyParGen. Initially, 90 PVDF and 30 PDA chains were packed in a box of dimension 5.2 nm × 5.2 nm × 5 nm, and the system (membrane) was equilibrated in the NP z T ensemble (with fixed pressure P in the z direction, allowing the box size to fluctuate perpendicular to the membrane) for 2.5 ns. The NP z T ensemble was applied to the system to allow the polymer membrane to match the piston area ( L x and L y ), thus making the system periodic in the lateral directions. After equilibration of the membrane, the thickness of the membrane varied around 2.6–3.5 nm resulting in a polymer density around 1.2–1.39 g/cc. After the construction of the membrane, we inserted water molecules along with ions in the feed side and pure water on the permeate side, as per the numbers given in the previous subsection. Two graphene sheets were used as pistons at the respective free surface sides of feed and permeate reservoirs. Inside the polymer, we added GO sheets to create the nanocomposite membrane. The GO sheets consisted of graphene sheets with 66 carbon atoms with 34 OH groups and two COOH groups attached to the carbon atoms along the edge and on the basal plane of the graphene sheet, respectively. The C/O ratio thus obtained for the GO was around 1.79, which is higher than the experimental value (0.678), but it was required to ensure the stability of the functionalized GO sheets in the MD simulations. Moving forward, rGO-I sheets were prepared by attaching six C 6 NH 8 O 3 groups and three C 6 NH 8 O 4 groups at the edge of the GO sheets. Note that these groups are seen in the experiments after GO reacts with 2-isocynatoethyl methacrylate. A similar methodology was followed after adding a different concentration of rGO-I sheets with 90 PVDF and 30 PDA chains to prepare an rGO-I@IPN_LC membrane. We also observed that, after equilibration of the rGO-I@IPN membrane in the NP z T ensemble, the interlayer distance was found to be around 0.60 nm, which is similar to what was observed in the experiments (0.62 nm). DECLARATIONS SUPPLEMENTARY INFORMATION Information about the characterization techniques, polarized optical microscopy (POM) images of rGO-I@IPN_LC dope solutions, N 2 adsorption/desorption isotherm of rGO-I@IPN_LC membrane, plots of pore size distributions employing the NLDFT method is shown in the inset, XRD pattern of dry rGO-I@IPN_LC and wet rGO-I@IPN_LC membranes, UV plot of water after 5 days and 90 days water exposure of GO and rGO-I@IPN_LC membrane respectively, representatives of the 2D X-ray scattering patterns of the rGO-I@IPN_LC membrane, deconvolution XPS value of C, N,O, and F, and temporal water permeation behaviour from MD simulations. Author contributions R.S.G., S.S.I., and D.P. contributed equally. R.S.G. and S.S.I. conceived the project idea, and performed the experiments. R.S.G and S.S.I. wrote the paper. D.P. carried out the MD simulations and analyzed the resulting data. A.G.R. supervised the MD simulation work. D.P. and A.G.R. wrote the simulations part of the paper. S.B. supervised the project and intellectual inputs came from S.B. and S.S.I. Disclosure statement The authors declare no competing financial interest. ACKNOWLEDGMENTS R.S.G would like to acknowledge the Ministry of Education for the Prime Minister’s Research Fellowship (PMRF). S.S.I. thanks the Science and Engineering Research Board (SERB) for the National Post Doctoral Fellowship (File No.: PDF/2021/000629). S.B. acknowledges the SERB Swarnajayanti Fellowship for carrying out the research. R.S.G and S.S.I. acknowledge the Department of Materials Engineering and CeNSE, Indian Institute of Science, for the opportunity to carry out research. A.G.R. acknowledges financial support from the SERB via a Core Research Grant (CRG) (File No.: CRG/2021/002792) and the Infosys Foundation, Bengaluru for an Infosys Young Investigator grant. D.P. acknowledges Bharath Desikan for his assistance with the Gromacs software. The authors acknowledge the computational facilities provided by the Supercomputer Education and Research Centre at the Indian Institute of Science for computing facilities. REFERENCES Pathan, S. et al. Fundamental Understanding of Ultrathin, Highly Stable Self-Assembled Liquid Crystalline Graphene Oxide Membranes Leading to Precise Molecular Sieving through Non-equilibrium Molecular Dynamics. ACS nano (2023). Samantaray, P. K., Sen Gupta, R. & Bose, S. Self‐Assembly in “Matrix‐Free” Functionalized Boron Nitride Sheets as Free‐Standing Thin Film Sieves for Stable Forward Osmosis and Robust Dye Removal Applications. Advanced Sustainable Systems , 2200385. Sen Gupta, R., Padmavathy, N. & Bose, S. The Journey of Water Remediation through Biomimetic Strategies: A Mechanistic Insight. Advanced Sustainable Systems 5 , 2100213 (2021). Van der Bruggen, B. Sustainable implementation of innovative technologies for water purification. Nature Reviews Chemistry 5 , 217-218 (2021). Faucher, S. et al. Critical knowledge gaps in mass transport through single-digit nanopores: A review and perspective. The Journal of Physical Chemistry C 123 , 21309-21326 (2019). Sharma, B. B. & Govind Rajan, A. How grain boundaries and interfacial electrostatic interactions modulate water desalination via nanoporous hexagonal boron nitride. The Journal of Physical Chemistry B 126 , 1284-1300 (2022). Tiwary, S. K., Singh, M., Chavan, S. V. & Karim, A. Graphene oxide-based membranes for water desalination and purification. npj 2D Materials and Applications 8 , 27 (2024). Padmavathy, N., Behera, S. S., Pathan, S., Das Ghosh, L. & Bose, S. Interlocked graphene oxide provides narrow channels for effective water desalination through forward osmosis. ACS applied materials & interfaces 11 , 7566-7575 (2019). Huang, H. et al. Ultrafast viscous water flow through nanostrand-channelled graphene oxide membranes. Nature communications 4 , 2979 (2013). Sun, P. et al. Selective ion penetration of graphene oxide membranes. ACS nano 7 , 428-437 (2013). Thebo, K. H. et al. Highly stable graphene-oxide-based membranes with superior permeability. Nature communications 9 , 1486 (2018). Li, W., Wu, W. & Li, Z. Controlling interlayer spacing of graphene oxide membranes by external pressure regulation. Acs Nano 12 , 9309-9317 (2018). Jamil, N. et al. Mixed matrix membranes incorporated with reduced graphene oxide (rGO) and zeolitic imidazole framework-8 (ZIF-8) nanofillers for gas separation. Journal of Solid State Chemistry 270 , 419-427 (2019). Alayande, A. B., Park, H. D., Vrouwenvelder, J. S. & Kim, I. S. Implications of chemical reduction using hydriodic acid on the antimicrobial properties of graphene oxide and reduced graphene oxide membranes. Small 15 , 1901023 (2019). Mohammed, S. A. et al. CO2/N2 selectivity enhancement of PEBAX MH 1657/Aminated partially reduced graphene oxide mixed matrix composite membrane. Separation and Purification Technology 223 , 142-153 (2019). Liu, Z., Xu, Z., Hu, X. & Gao, C. Lyotropic liquid crystal of polyacrylonitrile-grafted graphene oxide and its assembled continuous strong nacre-mimetic fibers. Macromolecules 46 , 6931-6941 (2013). Xu, Z. & Gao, C. Aqueous liquid crystals of graphene oxide. ACS nano 5 , 2908-2915 (2011). Zhang, Y. et al. Rapid fabrication by lyotropic self-assembly of thin nanofiltration membranes with uniform 1 nanometer pores. ACS nano 15 , 8192-8203 (2021). Yun, T., Jeong, G. H., Padmajan Sasikala, S. & Kim, S. O. 2D graphene oxide liquid crystal for real-world applications: Energy, environment, and antimicrobial. APL Materials 8 , 070903 (2020). Hegde, M. et al. Strong graphene oxide nanocomposites from aqueous hybrid liquid crystals. Nature Communications 11 , 830 (2020). Jalili, R. et al. Formation and processability of liquid crystalline dispersions of graphene oxide. Materials Horizons 1 , 87-91 (2014). Mahalingam, D. K., Wang, S. & Nunes, S. P. Graphene oxide liquid crystal membranes in protic ionic liquid for nanofiltration. ACS Applied Nano Materials 1 , 4661-4670 (2018). Akbari, A. et al. Large-area graphene-based nanofiltration membranes by shear alignment of discotic nematic liquid crystals of graphene oxide. Nature communications 7 , 10891 (2016). Guo, F. et al. Hydration-responsive folding and unfolding in graphene oxide liquid crystal phases. Acs Nano 5 , 8019-8025 (2011). Ma, F.-f. et al. Blend-electrospun poly (vinylidene fluoride)/polydopamine membranes: self-polymerization of dopamine and the excellent adsorption/separation abilities. Journal of Materials Chemistry A 5 , 14430-14443 (2017). Shao, L., Wang, Z. X., Zhang, Y. L., Jiang, Z. X. & Liu, Y. Y. A facile strategy to enhance PVDF ultrafiltration membrane performance via self-polymerized polydopamine followed by hydrolysis of ammonium fluotitanate. Journal of Membrane Science 461 , 10-21 (2014). Xu, L. Q., Yang, W. J., Neoh, K.-G., Kang, E.-T. & Fu, G. D. Dopamine-induced reduction and functionalization of graphene oxide nanosheets. Macromolecules 43 , 8336-8339 (2010). Mohammadi Ghaleni, M. et al. Fabrication of Janus membranes for desalination of oil-contaminated saline water. ACS applied materials & interfaces 10 , 44871-44879 (2018). Sa, K. et al. in IOP Conference Series: Materials Science and Engineering. 012055 (IOP Publishing). Wu, T. et al. Facile and low-cost approach towards a PVDF ultrafiltration membrane with enhanced hydrophilicity and antifouling performance via graphene oxide/water-bath coagulation. RSC advances 5 , 7880-7889 (2015). Tene, T. et al. Toward large-scale production of oxidized graphene. Nanomaterials 10 , 279 (2020). Gupta, R. S., Padmavathy, N., Agarwal, P. & Bose, S. pH-triggered bio-inspired membranes engineered using sequential interpenetrating polymeric networks for tunable antibiotic and dye removal. Chemical Engineering Journal , 136997 (2022). Muchtar, S., Wahab, M. Y., Mulyati, S., Arahman, N. & Riza, M. Superior fouling resistant PVDF membrane with enhanced filtration performance fabricated by combined blending and the self-polymerization approach of dopamine. Journal of Water Process Engineering 28 , 293-299 (2019). Chung, T. S., Teoh, S. K. & Hu, X. Formation of ultrathin high-performance polyethersulfone hollow-fiber membranes. Journal of membrane science 133 , 161-175 (1997). Wang, D.-M. & Lai, J.-Y. Recent advances in preparation and morphology control of polymeric membranes formed by nonsolvent induced phase separation. Current Opinion in Chemical Engineering 2 , 229-237 (2013). Guillen, G. R., Pan, Y., Li, M. & Hoek, E. M. Preparation and characterization of membranes formed by nonsolvent induced phase separation: a review. Industrial & Engineering Chemistry Research 50 , 3798-3817 (2011). Dutta, S., Gupta, R. S., Manna, K., Islam, S. S. & Bose, S. ‘Green-tea’extract soldered triple interpenetrating polymer network membranes for water remediation. Chemical Engineering Journal , 145008 (2023). Elbasuney, S., El-Sayyad, G. S., Tantawy, H. & Hashem, A. H. Promising antimicrobial and antibiofilm activities of reduced graphene oxide-metal oxide (RGO-NiO, RGO-AgO, and RGO-ZnO) nanocomposites. RSC advances 11 , 25961-25975 (2021). Li, B., Wang, S., Loh, X. J., Li, Z. & Chung, T.-S. Closed-loop recyclable membranes enabled by covalent adaptable networks for water purification. Proceedings of the National Academy of Sciences 120 , e2301009120 (2023). Lu, Y., Liu, W., Wang, K. & Zhang, S. Electropolymerized thin films with a microporous architecture enabling molecular sieving in harsh organic solvents under high temperature. Journal of Materials Chemistry A 10 , 20101-20110 (2022). Cseri, L. et al. Bridging the interfacial gap in mixed-matrix membranes by nature-inspired design: Precise molecular sieving with polymer-grafted metal–organic frameworks. Journal of Materials Chemistry A 9 , 23793-23801 (2021). Cheng, Y.-T., Chu, K.-C., Tsao, H.-K. & Sheng, Y.-J. Size-dependent behavior and failure of young’s equation for wetting of two-component nanodroplets. Journal of Colloid and Interface Science 578 , 69-76 (2020). Seo, K. & Kim, M. in Surface energy (InTechOpen, 2015). Elimelech, M., Chen, W. H. & Waypa, J. J. Measuring the zeta (electrokinetic) potential of reverse osmosis membranes by a streaming potential analyzer. Desalination 95 , 269-286 (1994). Pérez-Mitta, G. et al. Polydopamine meets solid-state nanopores: a bioinspired integrative surface chemistry approach to tailor the functional properties of nanofluidic diodes. Journal of the American chemical Society 137 , 6011-6017 (2015). Mun, S. J. et al. Tailored growth of graphene oxide liquid crystals with controlled polymer crystallization in GO-polymer composites. Nanoscale 13 , 2720-2727 (2021). Wong, G. C. et al. Lamellar phase of stacked two-dimensional rafts of actin filaments. Physical review letters 91 , 018103 (2003). Kumar, P., Maiti, U. N., Lee, K. E. & Kim, S. O. Rheological properties of graphene oxide liquid crystal. Carbon 80 , 453-461 (2014). Mezzenga, R. et al. Shear rheology of lyotropic liquid crystals: a case study. Langmuir 21 , 3322-3333 (2005). Deng, J., You, Y., Bustamante, H., Sahajwalla, V. & Joshi, R. K. Mechanism of water transport in graphene oxide laminates. Chemical science 8 , 1701-1704 (2017). Gupta, R. S. et al. Copper-substituted polyoxometalate-soldered interpenetrating polymeric networks membranes for water remediation. Chemical Engineering Journal 461 , 141949 (2023). Li, R., Wu, Y., Shen, L., Chen, J. & Lin, H. A novel strategy to develop antifouling and antibacterial conductive Cu/polydopamine/polyvinylidene fluoride membranes for water treatment. Journal of colloid and interface science 531 , 493-501 (2018). Sun, P. et al. Selective trans-membrane transport of alkali and alkaline earth cations through graphene oxide membranes based on cation− π interactions. Acs Nano 8 , 850-859 (2014). Hu, W. et al. Graphene-based antibacterial paper. ACS nano 4 , 4317-4323 (2010). Akhavan, O. & Ghaderi, E. Toxicity of graphene and graphene oxide nanowalls against bacteria. ACS nano 4 , 5731-5736 (2010). Abadikhah, H., Naderi Kalali, E., Khodi, S., Xu, X. & Agathopoulos, S. Multifunctional thin-film nanofiltration membrane incorporated with reduced graphene oxide@ TiO2@ Ag nanocomposites for high desalination performance, dye retention, and antibacterial properties. ACS applied materials & interfaces 11 , 23535-23545 (2019). Samantaray, P. K., Baloda, S., Madras, G. & Bose, S. A designer membrane tool-box with a mixed metal organic framework and RAFT-synthesized antibacterial polymer perform in tandem towards desalination, antifouling and heavy metal exclusion. Journal of Materials Chemistry A 6 , 16664-16679 (2018). Liu, S. et al. Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress. ACS nano 5 , 6971-6980 (2011). Bielawski, C., Dreyer, D., Park, S. & Ruoff, R. The chemistry of grapheme oxide. Chem. Soc. Rev 39 , 228-240 (2010). Guo, F., Mukhopadhyay, A., Sheldon, B. W. & Hurt, R. H. Vertically aligned graphene layer arrays from chromonic liquid crystal precursors. Advanced materials 23 , 508-513 (2011). Hurt, R. H. & Chen, Z.-Y. LIQUID CRYSTALS AND CARBON MATERIALS. Physics today 53 , 39-44 (2000). De Gennes, P.-G. & Prost, J. The physics of liquid crystals . (Oxford university press, 1993). Mukherjee, R., Bhunia, P. & De, S. Impact of graphene oxide on removal of heavy metals using mixed matrix membrane. Chemical Engineering Journal 292 , 284-297 (2016). Stankovich, S., Piner, R. D., Nguyen, S. T. & Ruoff, R. S. Synthesis and exfoliation of isocyanate-treated graphene oxide nanoplatelets. Carbon 44 , 3342-3347 (2006). Zeron, I., Abascal, J. & Vega, C. A force field of Li+, Na+, K+, Mg2+, Ca2+, Cl−, and SO42− in aqueous solution based on the TIP4P/2005 water model and scaled charges for the ions. The Journal of chemical physics 151 (2019). Cheng, A. & Steele, W. Computer simulation of ammonia on graphite. I. Low temperature structure of monolayer and bilayer films. The Journal of chemical physics 92 , 3858-3866 (1990). Abascal, J. L. & Vega, C. A general purpose model for the condensed phases of water: TIP4P/2005. The Journal of chemical physics 123 (2005). Jorgensen, W. L., Maxwell, D. S. & Tirado-Rives, J. Development and testing of the OPLS all-atom force field on conformational energetics and properties of organic liquids. Journal of the American Chemical Society 118 , 11225-11236 (1996). Scheme Scheme 1 is available in the Supplementary Files section. Additional Declarations There is NO Competing Interest. Supplementary Files SI3May2024.docx Supplementary file Scheme1.jpg Scheme 1. Chemical reaction involved in the synthesis of rGO-I particles and subsequent fabrication of the rGO-I@IPN_LC membrane via the non-solvent induced phase separation technique. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4381911","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":300941792,"identity":"1780dda2-ddbe-4b71-82e6-cfab99bd27b6","order_by":0,"name":"Suryasarathi Bose","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAArUlEQVRIiWNgGAWjYDACCRBRIcGDzCVGyxmStTC2keIu+dnNhz98nGchI99+gPHDDwaLPIJaDO4cS5OcuU2Cx+BMArNkD4NEMWEtEjlmzLwgLUAXSgPdmdhA0GEzcow//50jwSM/g4H5N1FaGG7kGEgzNgBD7AYDG3G2gP3Scwzkl8Q2yx4DYhwGCrEfNXX28u2HD9/4UVFHhMMQgBGo2IAE9aNgFIyCUTAKcAMAniUy7r9aOQUAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-8043-9192","institution":"Indian Institute of Science Bangalore","correspondingAuthor":true,"prefix":"","firstName":"Suryasarathi","middleName":"","lastName":"Bose","suffix":""},{"id":300941793,"identity":"39449aab-550e-4d68-bc21-16d076b87344","order_by":1,"name":"Ria Sen Gupta","email":"","orcid":"","institution":"Indian Institute of Science Bangalore","correspondingAuthor":false,"prefix":"","firstName":"Ria","middleName":"Sen","lastName":"Gupta","suffix":""},{"id":300941794,"identity":"c5ed4bc7-e35d-4431-b260-3914b2300619","order_by":2,"name":"Sk Safikul Islam","email":"","orcid":"","institution":"Indian Institute of Science","correspondingAuthor":false,"prefix":"","firstName":"Sk","middleName":"Safikul","lastName":"Islam","suffix":""},{"id":300941795,"identity":"db5a83a3-fede-47e1-9af4-1053ac8bf7a7","order_by":3,"name":"Dhondi Pradeep","email":"","orcid":"","institution":"IISc","correspondingAuthor":false,"prefix":"","firstName":"Dhondi","middleName":"","lastName":"Pradeep","suffix":""},{"id":300941796,"identity":"4b47f6ce-de7c-42ec-bd61-cca663504b3a","order_by":4,"name":"Ananth Govind Rajan","email":"","orcid":"https://orcid.org/0000-0003-2462-0506","institution":"Indian Institute of Science","correspondingAuthor":false,"prefix":"","firstName":"Ananth","middleName":"Govind","lastName":"Rajan","suffix":""}],"badges":[],"createdAt":"2024-05-07 09:33:32","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4381911/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4381911/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":57187230,"identity":"eb0f11c4-5950-45e1-9d24-f12fa9234258","added_by":"auto","created_at":"2024-05-27 06:17:35","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3080068,"visible":true,"origin":"","legend":"\u003cp\u003eLC phase in rGO-I@IPN_LC dope solution exhibited due to introduction of LC rGO-I sheets. The ordered phases were retained in the IPN membrane along with the appearance of new lamellar phases. Formation of IPN resulted in a robust membrane with arrested swelling and configurational entropy. It also aided effective ion rejection performance with antibacterial properties and cytocompatibility\u003c/p\u003e","description":"","filename":"image1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/b36e0a9f595ef6578b5715b3.jpg"},{"id":57186897,"identity":"266c0c62-66b7-48f9-b54c-ad026cbe3441","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":2156275,"visible":true,"origin":"","legend":"\u003cp\u003eAssessing the fabricated rGO-I sheets and the rGO-I@IPN_LC membranes. (a) FTIR spectra, (b) XPS spectra, and (c) XRD spectra of GO, rGO-I sheets, IPN, and rGO-I@IPN_LC membranes. (d) TGA profile of rGO-I sheets, IPN, and rGO-I@IPN_LC membrane. (e) DMA analysis of IPN and rGO-I@IPN_LC membrane.\u003c/p\u003e","description":"","filename":"image2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/c6c3269351a833d02a0f2ea8.jpg"},{"id":57186905,"identity":"e8edba51-cbe5-4ca9-bc05-7de4cb9bd525","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":4870664,"visible":true,"origin":"","legend":"\u003cp\u003eSEM micrographs of the rGO-I sheets and the membranes. (a,b) Surface morphology of rGO-I sheets and its EDAX spectra, respectively. (c,d,e) Neat IPN membranes surface, cross-section images, and EDAX spectra, respectively. (f,g,h) rGO-I@IPN_LC membrane’s surface, cross-section, and EDAX analysis, respectively. The cross-section images of both neat IPN and rGO-I@IPN_LC membranes clearly indicate the presence of entangled chains.\u003c/p\u003e","description":"","filename":"image3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/9c34317716ee4910c3e97676.jpg"},{"id":57186900,"identity":"3914d563-16ae-4634-aea6-696178ddc688","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":217150,"visible":true,"origin":"","legend":"\u003cp\u003ePerformance and properties of the rGO-I@IPN_LC membrane. (a) Molecular weight cut-of analysis of the rGO-I@IPN_LC membrane (b) Zeta potential of neat IPN, rGO-T sheets, rGO-I@IPN_LC membrane, and charge triggered rGO-I@IPN_LC membrane (c) Water contact angle and (d,e) AFM images of neat IPN and rGO-I@IPN_LC membranes, respectively\u003c/p\u003e","description":"","filename":"image4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/248fa49f41c98dea8a4edd11.jpg"},{"id":57187231,"identity":"d439dc1c-7d09-4d80-b771-37e0dcb9bc89","added_by":"auto","created_at":"2024-05-27 06:17:35","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":2632150,"visible":true,"origin":"","legend":"\u003cp\u003ePolarized optical microscope images of rGO-I@IPN_LC dope solutions at different concentrations. (a) 1mg/mL, (b) 3 mg/mL, (c) 5 mg/mL, and (d) 7.5 mg/mL.\u003c/p\u003e","description":"","filename":"image5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/48d10c24aefc0f4a7b5c7aac.jpg"},{"id":57186901,"identity":"79ff7e8d-c8e2-4236-8c12-9619dbf2b2f3","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1771165,"visible":true,"origin":"","legend":"\u003cp\u003e(a) SAXS of rGO-I dispersion at 7.5 mg/mL concentration. (b) SAXS profile of the rGO-I@IPN_LC membrane. (c) Evolution of complex viscosity with the shear rate at different rGO-I concentration in rGO-I@IPN_LC dope solutions. (d) Zero shear viscosity vs. increasing rGO-I concentration in IPN dope solution\u003c/p\u003e","description":"","filename":"image6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/d05e65647dae9dd66458fdfb.jpg"},{"id":57186906,"identity":"1270740b-b854-4eeb-8ce5-be11c160733b","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":272082,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Membrane stability in terms of pure water flux experiments for a period of 3 weeks. (b) Antifouling characteristics of the neat IPN and rGO-I@IPN_LC membrane by flux recovery ratio. (c) Salt rejection, (d) chlorine tolerance obtained using rGO-I@IPN_LC membrane, (e) dye rejection, and (f) antibiotic removal via using rGO-I@IPN_LC membranes.\u003c/p\u003e","description":"","filename":"image7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/b2632e851af26abf64f58c39.jpg"},{"id":57186907,"identity":"18251f81-fc96-445d-adbe-57685711995c","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":677670,"visible":true,"origin":"","legend":"\u003cp\u003e(a, b) Digital images for the bacterial colonies formed in the TSA plates in the neat IPN, the control samples, and rGO-I@IPN_LC membranes for E. coli (top row) and S.aureus (bottom row). (c) Cytotoxicity evaluation of the rGO-I@IPN_LC membrane against mammalian cell lines (L929) using MTT assay.\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/a71429f57df8c9260182c3a0.png"},{"id":57186908,"identity":"2cd3830d-a3f9-4958-94b5-a776f671d002","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":571245,"visible":true,"origin":"","legend":"\u003cp\u003eMD simulations of water permeation via the rGO-I@IPN membranes. (a) Schematic of the non-equilibrium MD setup with an rGO-I@IPN membrane, a saline water reservoir (feed side), and a pure water reservoir (permeate side), confined by two pistons. The feed side is subjected to a pressure of P = 100 MPa, while the permeate side has a pressure of P\u003csub\u003eatm\u003c/sub\u003e = 1.013 bar. Chloride ions are in green, sodium ions in blue, oxygens in red, hydrogens in white, and carbons in cyan colour. (b-c) Plot of the number of water molecules permeated across different membranes over time for (b) NaCl and (c) Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e salt solutions. (d) Comparative study of water permeance from MD simulations with experimental data for NaCl and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e aqueous salt solution.\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/e7e2ceea46979d33d8ebec56.png"},{"id":57186902,"identity":"f114001a-9bc7-454f-a902-36187a04650c","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1154444,"visible":true,"origin":"","legend":"\u003cp\u003eSimulation results for ion rejection by the different membranes. The fluctuation in the number of positively and negatively charged ions in different simulation regions over time, with the feed side under a pressure of 100 MPa, for (a) NaCl and (b) Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e salt solutions, in the feed, membrane, and permeate regions.\u003c/p\u003e","description":"","filename":"image10.png","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/78bce19fe38ee9433051d389.png"},{"id":58290808,"identity":"5e8c7045-3c4d-4c0e-b777-b0237d2c4260","added_by":"auto","created_at":"2024-06-13 13:33:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":18256962,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/38376212-22e2-4932-a98e-758ef3d189a8.pdf"},{"id":57186903,"identity":"56fd468a-6b6a-4936-9aac-d7c973602bbb","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":26253697,"visible":true,"origin":"","legend":"\u003cp\u003eSupplementary file\u003c/p\u003e","description":"","filename":"SI3May2024.docx","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/7e21d04770be2cb6e52abbf0.docx"},{"id":57186899,"identity":"323e80cb-3ac7-4045-a239-b56b1f56070b","added_by":"auto","created_at":"2024-05-27 06:09:35","extension":"jpg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":2833948,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1.\u003c/strong\u003e Chemical reaction involved in the synthesis of rGO-I particles and subsequent fabrication of the rGO-I@IPN_LC membrane via the non-solvent induced phase separation technique.\u003c/p\u003e","description":"","filename":"Scheme1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4381911/v1/9b1c1d08aa0cc0f88a429791.jpg"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Sequential interpenetrating polymer network confines shear-aligned graphene oxide liquid crystals enabling precise molecular sieving","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eDepletion of freshwater aquifers has continued to pose significant challenges for the global population, and thus purification of the existing water resources, including brine, brackish water, wastewater, and seawater, has become the focus of recent\u003csup\u003e1\u003c/sup\u003e research developments.\u003csup\u003e2,3\u003c/sup\u003e Membrane technology, being one of the most facile and effective separation techniques, represents a promising solution to gain considerable respite in this direction. New membrane materials coupled with easily scalable synthetic pathways are in heavy demand to overcome the roadblocks set by the current state-of-the-art RO membranes.\u003csup\u003e4\u003c/sup\u003e Disintegration upon exposure to harsh chemical environments and biofouling contribute majorly to the impairment and ultimate failure of commercial membranes. Two-dimensional (2D) nanomaterials have gained immense popularity in terms of mitigating fouling issues and enabling high-throughput and high-selectivity membranes.\u003csup\u003e5\u0026ndash;7\u003c/sup\u003e In this regard, graphene oxide (GO), the \u0026ldquo;next-generation wonder material,\u0026rdquo; has gained prominence in research efforts and offers exceptional potential in separation applications.\u003csup\u003e8\u003c/sup\u003e High hydrophilicity, tuneable functionality, mechanical integrity, and flexibility provide ample opportunities for efficient ion and molecular sieving mechanisms.\u003csup\u003e9\u0026ndash;11\u003c/sup\u003e However, disintegration under high operating transmembrane pressure and swelling of the nanochannels due to water intercalation have been reported to be the major engineering roadblocks in GO membrane upscaling. Efforts for controlling the swelling phenomenon have been mainly directed toward crosslinking and chemical reduction, which in general comes with challenges such as cytocompatibility,\u003csup\u003e11,12\u003c/sup\u003e Additionally, free-standing GO membranes are prone to corrugation via oxygen-containing moieties and hence need to be protected via embedding in a suitable polymeric matrix.\u003csup\u003e13\u003c/sup\u003e However, owing to compatibility issues between neat GO and the matrix arising from mismatched surface energies and aggregation of GO sheets, phase separation is evident, leading to deterioration of the desired properties. In this light, chemical modification of GO sheets is inevitable to enable miscibility. A mild and partial reduction of GO (with reduced interlayer spacing), coupled with appropriate functionality can solve the issues mentioned above.\u003csup\u003e14,15\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eAlthough GO membranes have been extensively explored in the recent past for their separation performance, a comparatively new research direction is the fabrication of GO-based lyotropic liquid crystalline materials.\u003csup\u003e16\u0026ndash;22\u003c/sup\u003e These self-assembled highly ordered GO-based stacked structures exhibit superior mechanical properties owing to the presence of stable secondary interactions and have thermodynamically defined and characteristic length-scale domains, which aid in striking a perfect balance between permeability and specific selectivity. So far, free-standing GO liquid crystalline (LC) membranes have been reported in the literature with insignificant rejection efficiencies and requiring high concentrations of material for rendering LC phases.\u003csup\u003e23\u003c/sup\u003e In our previous work, a reactive liquid crystal GO-based monomer was explored which upon ultraviolet (UV) crosslinking resulted in a robust and chlorine-tolerant lyotropic LC membrane with promising separation efficiencies.\u003csup\u003e1\u003c/sup\u003e However, these high-performance free-standing membrane modules require external stimulus (UV, magnetic stirring, shearing, etc.) for demonstration of oriented structures and just like neat free-standing GO can undergo corrugation and suffer from brittle fracture under operating conditions.\u003c/p\u003e \u003cp\u003eAs a comprehensive remedy, which is usually not realizable using the conventional approaches discussed above, a membrane incorporating partially reduced and functionalized GO LC sheets with a sequential interpenetrating polymeric network (IPN) can offer a quantum leap of advancement in terms of the desired membrane properties. Accordingly, in this work, we report for the first time the engineering amalgamation of functionalized GO LC sheets and an IPN membrane derived from polyvinylidene fluoride (PVDF) and mussel-inspired dopamine. 2-Isocyanate ethyl methacrylate functionalized GO sheets were reduced via a mild and green reducing agent (green tea leaves). This functionalization helped in bringing down the interlayer-spacing of the neat GO sheets from 8 to 6 \u0026Aring;. Additionally, the functionalized reduced GO (rGO-I) sheets were able to demonstrate ordered nematic phases at much lower concentration than those reported in the literature and augmented the compatibility with the polymeric matrix. The IPN on the other hand, was instrumental in triggering the orientation and arresting the LC sheets inside the matrix without the need for any external stimulus and protected the rGO-I sheets from getting corrugated or delaminated besides maintaining the stacking periodicity, even after continuous exposure to aqueous environments. Fundamentally, the integration of the LC sheets and the sequential IPN membrane was actuated by anchoring the rGO-I sheets with the dopamine monomer prior to polymerization via electrostatic assembly. Subsequently, upon in-situ sequential polymerization and membrane fabrication, the rGO-I sheets were aligned and arrested at nanoconfined length scales that are required for precise molecular separation. Apart from electrostatic forces, the secondary interactions, such as dipole-dipole and π-π interactions between the dopamine moieties and the rGO-I sheets reinforced the interlayer bonding and helped in shaping the macroscopic stability of the LC membranes. The presence of the IPN helped in manipulating the LC phase to produce long-range order via nanoconfinement and the final membranes exhibit similar transitions described by Onsager\u0026rsquo;s hard-plate theory.\u003csup\u003e24\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eWe show that the rGO-I@IPN_LC dope solutions show LC behavior and exhibit nematic phases as corroborated via rheological evaluations and small-angle X-ray scattering (SAXS) measurements. On the other hand, after fabrication of shear-aligned rGO-I@IPN_LC, the membranes retained their nematic LC phases with the existence of new lamellar phases, which is also evident from the SAXS. Additionally, the presence of zwitterionic polydopamine in the IPN matrix helped in regulating the surface charge of the membrane which further aided separation efficacy. The membranes were found to be extremely stable in terms of ion and molecular sieving efficacy and demonstrated high water flux (145 LMH, i.e., Lm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003eh\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). They were resistant to chlorine attack, were cytocompatible, had antibacterial properties, and exhibited excellent mechanical integrity at high transmembrane pressure. All-atom molecular dynamics simulations were utilized to investigate the permeation of water and the rejection of ions, offering intricate insights into the molecular mechanisms underlying ionic sieving facilitated by IPN membranes incorporating GO-LC. The adoption of such a hybrid mesophase route helped in achieving such robust membranes and paved the way for the potential designing of robust and sustainable GO-based LC membranes for water purification applications. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e demonstrates the salient features of the fabricated membrane. The rGO-I@IPN_LC dope solution demonstrated the presence of a nematic phase. The ordered phases (nematic and lamellar) were retained post IPN evolution, wherein IPN architecture not only helped in retaining the LC phase but also arrested swelling of the rGO-I sheets.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"2. RESULTS AND DISCUSSION","content":"\u003cp\u003e\u003cstrong\u003eDesigner LC membranes with long-range periodicity\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThe rGO-I LC was designed by partial and mild reduction of the GO-I sheets and was then added to the IPN dope solution consisting of PVDF and dopamine. The negatively charged rGO-I LC particles got electrostatically bound to dopamine owing to strong attractive forces between the two counter-charged species. Consequently, polymerization of the rGO-I-anchored dopamine occurred and led to long-range ordering of rGO-I LC sheets.\u003c/p\u003e\n\u003cp\u003eThe changes in the chemical environment brought about by the LC phase was probed via FTIR analysis shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea. The fabricated rGO-I LC sheets retained the characteristic peaks of neat GO (observed at 3200, 1721, 1612, and 1044 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponding to hydroxyl -OH, carbonyl -C\u0026thinsp;=\u0026thinsp;O, C\u0026thinsp;=\u0026thinsp;C, and C-O stretching, respectively) and additionally showed two new peaks at 1295 and 1167 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the stretching vibrations of amide C-O and C-N. This is due to the successful reaction with 2-isocyanatoethyl methacrylate. However, the intensity of the oxygen containing peaks\u003csup\u003e25\u003c/sup\u003e such as -OH, -C\u0026thinsp;=\u0026thinsp;O, and C-O decreased owing to the mild reduction reaction with green tea. Additionally, the absence of any isocyanate peaks (~\u0026thinsp;2275\u0026thinsp;\u0026minus;\u0026thinsp;2263 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) supplemented the successful covalent interaction with 2-isocyanatoethyl methacrylate. Upon the inclusion of the rGO-I sheets into the IPN, new peaks arising from the components of the matrix appeared. The new peaks could be ascribed to the strong -CH\u003csub\u003e2\u003c/sub\u003e bending and -CF\u003csub\u003e2\u003c/sub\u003e stretching of PVDF (1402 and 1167 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively), including a broad hump around 3369 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e from the -OH and -NH stretching of the polydopamine catecholamines, and two peaks centred around 1630\u0026thinsp;\u0026minus;\u0026thinsp;1548 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e from the scissoring as well as bending vibrations of N-H bonds.\u003csup\u003e26\u003c/sup\u003e The overlapping peaks and slight peak shifting in the final membrane further indicated the successful electrostatic inclusion of the rGO-I sheets and their interaction with the IPN network.\u003c/p\u003e\n\u003cp\u003eFindings from the XPS spectra (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb) further strengthened the FTIR evaluations and shed light onto the intrinsic binding energies which characterized the strong electrostatic and capping interaction\u003csup\u003e27\u003c/sup\u003e of the LC sheets with the designer IPN membrane. The studies mainly indicated the presence of carbon, nitrogen, oxygen, and fluorine. The main difference between the GO sheets and the rGO-I LC sheets lie in the fact that the O 1s intensity decreased slightly as compared to neat GO owing to the mild reduction process. The amide bond present in rGO-I sheets is characterised by a peak of N 1s at 400.4 eV seen in the deconvoluted spectra. Upon deconvoluting the C 1s core spectra for rGO-I sheets (\u003cstrong\u003eFig. \u003cspan class=\"InternalRef\"\u003eS1\u003c/span\u003ee\u003c/strong\u003e), three peaks were obtained around 284.68, 286, and 288.65 eV, corresponding to the presence of sp\u003csup\u003e2\u003c/sup\u003e/sp\u003csup\u003e3\u003c/sup\u003e hybridised carbon, carbonyl C-O, and O-C\u0026thinsp;=\u0026thinsp;O bonds, respectively. Also, the core C 1s spectra for the rGO-I@IPN_LC (\u003cstrong\u003eFig. \u003cspan class=\"InternalRef\"\u003eS1\u003c/span\u003ea\u003c/strong\u003e) membrane along with the peaks mentioned above showed additional peaks at ~\u0026thinsp;290.84 eV for the -CF\u003csub\u003e2\u003c/sub\u003e bond, 288.34 eV for O-C\u0026thinsp;=\u0026thinsp;O bonds, 285.75 eV C-O bonds, and 284.70 eV for sp2/sp3 hybridised carbon.\u003csup\u003e28\u003c/sup\u003e The presence of C-N bonds corroborated the interaction between the rGO-I sheets and the dopamine moieties. Another notable difference between the rGO-I sheets and the rGO-I@IPN_LC membrane was the fact that the IPN membrane had a strong presence of F 1s coming from the PVDF component which was absent in the neat rGO-I sheets. The presence of a peak at 532.55 eV in the deconvoluted O 1s spectra further substantiated the presence of oxygen on the surface of the membranes. No peak shifting was observed after dye removal experiments, which further stressed upon the reusability of the system. Only minor reduction in peak intensities were observed which could be attributed to interaction with the dye molecules.\u003c/p\u003e\n\u003cp\u003eThe effect of 2-isocynatoethyl methacrylate (ICM) incorporation on the interlayer distance of rGO-I compounds was evaluated by XRD (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec). The GO sheets exhibited an intense peak at 9.94\u0026deg;, corresponding to the (001) plane, with an interlayer distance of 0.89 nm. Upon reacting the modified GO-I sheets using \u0026ldquo;green tea extract\u0026rdquo;, a limited reduction was observed in the oxygenated functional groups, which led to the appearance of a 2-theta peak at 14.36\u0026deg;, indicating the formation of crystalline yet partially reduced rGO sheets with an interlayer distance of 0.62 nm. The fresh peak (weak) at 30.68\u0026deg; (0.29 nm) hinted at the presence of reduced GO-I nanosheets.\u003csup\u003e29\u003c/sup\u003e The IPN membrane exhibited a peak at around 20.56\u0026ordm; due to the semi-crystalline nature of PVDF.\u003csup\u003e30\u003c/sup\u003e Finally, in the case of rGO-I@IPN_LC membranes, peaks corresponding to both rGO-I and IPN were present, indicating the successful insertion of partially rGO-I into the IPN matrix. The IPN matrix triggered the orientation of the LC sheets and also retained the interlayer-spacing of the LC sheets. In addition, we assessed the interlayer spacing of dry and wet rGO-I@IPN_LC membranes. However, the XRD spectra demonstrated no change in the interlayer-spacing of the membranes even after being dipped in water for a period of 90 days. This observation further supported the stability of the rGO-I@LC membranes which neither leached nor delaminated upon elongated periods of exposure to aqueous environments (\u003cstrong\u003eFig. S2\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eThe thermal profile and the mechanical integrity of the synthesized sheets and the membranes was evaluated from thermogravimetric analysis (TGA) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed) and dynamic mechanical analysis (DMA) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ee). As observed from the TGA profiles, the rGO-I sheets record a weight loss of nearly 3% before 100 \u0026ordm;C due to the presence of physisorbed water molecules. The significant weight loss in the range 200\u0026ndash;250 \u0026ordm;C and weaker loss in the range 250\u0026ndash;800 \u0026ordm;C can be attributed to the degradation of less stable (CO, CO\u003csub\u003e2\u003c/sub\u003e, and H\u003csub\u003e2\u003c/sub\u003eO) moieties and stable oxygenated groups. However when compared to neat GO,\u003csup\u003e31\u003c/sup\u003e the rGO-I sheets exhibit greater stability due to stronger van der Waals interactions between the sheets owing to the mild reduction in the oxygen containing functional groups. Upon successful tagging of the rGO-I sheets with the IPN, the thermal behaviour becomes similar to that of neat IPN,\u003csup\u003e32\u003c/sup\u003e however the Tmax (temperature for the onset of maximum degradation) increased by 20\u0026ndash;30 \u0026ordm;C. The tagging enabled an inclusion of 20% of the rGO-I sheets into the IPN matrix. We can thus draw an inference that the LC sheet inclusion aided the thermal property of the membrane and did not impair its thermal stability.\u003c/p\u003e\n\u003cp\u003eA comparative DMA study was performed to gauge the effectiveness of the rGO-I LC sheet inclusion inside the IPN in terms of mechanical robustness. From the storage modulus versus temperature plots, it was observed that the presence of the sheets increased the storage modulus of the neat IPN membranes from 140 MPa to nearly 200 MPa. This increment can be mainly ascribed to the presence of the oriented LC sheets.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEvolution of the morphology and surface properties in the rGO-I@IPN_LC membrane\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eMorphological evolutions were captured via a FESEM equipped with an EDX detector. The micrographs helped in providing a holistic understanding pertaining to the pore size reduction pathways. Here, the relatively large rGO-I (lateral dimension\u0026thinsp;=\u0026thinsp;1250 nm) (\u003cstrong\u003eFig. S3\u003c/strong\u003e) sheets get anchored to the dopamine monomers via electrostatic interaction and when this anchored dopamine polymerizes via auto-oxidative polymerization, a dense network of polydopamine (PDA) aligned the rGO-I LC sheets and arrested swelling. The simultaneous diffusion of the rGO-I-anchored dopamine monomer followed by the nucleation and growth of polydopamine into the hydrophobic pore channels of PVDF ensured and further strengthened the pore size reduction mechanism.\u003csup\u003e33\u003c/sup\u003e Nonsolvent-induced phase separation (NIPS) cast membranes are characterized by a smooth surfaces, few nodules and the cross-section is populated with finger-like macro voids which arises owing to the quick phase inversion process and rapid exchange of solvent-nonsolvent in the coagulation bath.\u003csup\u003e34\u0026ndash;36\u003c/sup\u003e However, after formation of an IPN, the surface is completely covered by the PDA and the surface roughness (more hydrophilicity) and asymmetry increases which is evident from the contact angle values (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec). The cross-section on the other hand for neat IPN membrane marks the presence of entangled networks and completely suppresses the finger and sponge-like morphology, which is a qualitative feature of IPNs.\u003csup\u003e37\u003c/sup\u003e The formation of the successful interpenetrated structure is also hinted upon by the suppression of macroscopic phase separation, an intrinsic property of IPNs. In the micrographs of the rGO-I LC sheets, ultrathin, wrinkled structures with distinct edges were observed, which is quite similar to rGO sheets reported in literature.\u003csup\u003e38\u003c/sup\u003e Upon their incorporation into the matrix, the surface features seem to change drastically. The rGO-I@IPN_LC membrane is characterized by increased surface roughness due to the rGO-I inclusions. When estimated via ImageJ software, it was observed that the pore sizes of the rGO-I@IPN_LC membrane reduced significantly to ~\u0026thinsp;7 nm as compared to 300\u0026ndash;500 nm for the neat IPN membrane. The obtained pore sizes were analogous to the data obtained from MWCO and BET analysis (\u003cstrong\u003eFig. S5\u003c/strong\u003e) and could effectively serve as nanofiltration membranes. The presence of the rGO-I LC sheets did not hamper the interconnected structure of the IPN membrane, and this was evidenced from the cross-section image of the rGO-I@IPN_LC membrane. The dense skin layer (40 \u0026micro;m) and the interconnected networks of the polymeric chains facilitate water transport but at the same time, the presence of the large sheets work in tandem to restrict the passage of the ionic species.\u003csup\u003e39\u003c/sup\u003e EDAX spectra revealed the elemental composition of the neat IPN (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ee\u003cstrong\u003e)\u003c/strong\u003e and the rGO-I@IPN_LC (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eh\u003cstrong\u003e)\u003c/strong\u003e membranes. The substantial increment in the elemental intensities of C, N, and O further corroborated the successful integration of the rGO-I LC sheets into the IPN architecture. We additionally investigated the EDAX spectra of the membranes after MB and CR dye rejection (\u003cstrong\u003eFig. S11a,b\u003c/strong\u003e). Diametrically opposite observations were obtained for the oppositely charged dyes. Although elemental footprint of the MB dye molecules were captured in the spectra, the footprint for the CR dyes was strategically absent, which further substantiates the dye rejection mechanism described in detail in the performance section.\u003c/p\u003e\n\u003cp\u003eThe surface of the membranes was further evaluated using nitrogen adsorption-desorption experiments at 77.35 K (\u003cstrong\u003eFig. S5\u003c/strong\u003e). The average pore diameter or mean pore size was the metric that was calculated from the isotherms. The isotherm corresponded to the type IV pattern according to IUPAC nomenclature with a characteristic hysteresis loop appearing in the multilayer range. The shape of the hysteresis loop was most likely caused by capillary condensation in the mesoporous structures. The incorporation of the rGO-I was expected to result in a decrease in pore size. The average pore diameter of the rGO-I@IPN_LC membrane was found to be around ca. 6.96 nm.\u003csup\u003e40,41\u003c/sup\u003e The porous rGO-I@IPN_LC membrane with \u0026pi;-conjugated skeletons, impressive pore size, and permanent porosity is deemed to pave the pathway for the construction of next-generation membranes for molecular sieving.\u003c/p\u003e\n\u003cp\u003eTo supplement the pore size measurements obtained from BET measurements, MWCO analysis (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea) was performed using a range of neutral solutes (molecular weight ranging from 300\u0026ndash;1400 Da). In brief, 10 ppm solutions of the neutral solutes were taken and their rejection efficiencies were evaluated using Eq.\u0026nbsp;(4). From the studies it was observed that the membranes could reject 73% of Giemsa stain, 80% of Sudan IV, 85% of tetracycline, 89% of oxytetracycline, 98% of azithromycin and 99% of vitamin B\u003csub\u003e12\u003c/sub\u003e. The rejection of these neutral solutes were solely based on the pore sizes and from the rejection studies it can be roughly concluded that the MWCO of the membranes lie in the range of 450\u0026ndash;1400 Da and hence the membranes are ought to have a pore size in the range of nearly 7 nm, which further supports the BET results obtained before.\u003c/p\u003e\n\u003cp\u003eApart from the features mentioned above, surface properties and charge play a major role in determining the end-use application of the membrane and also its intrinsic properties. Hydrophilic membranes are characterised by the heavy adsorption of water molecules on its surface thus generating a thick hydration layer which is essential for eliminating fouling issues. Thus, the evaluation of membrane nature is crucial in deciding its fate for long-term operation. With the help of a contact angle goniometer and deploying the sessile drop method, the water contact angle (WCA) values were studied which can be directly correlated to surface hydrophilicity/hydrophobicity via Young\u0026rsquo;s equation.\u003csup\u003e42\u003c/sup\u003e The rGO-I@IPN_LC membranes (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec) were found to exhibit a WCA value of 48\u0026ordm; which was nearly 18\u0026ordm; lesser than that of neat IPN. The significant enhancement in the hydrophilicity of the membranes can be attributed to the introduction of larger amounts of hydrophilic -OH and -NH and polar -C\u0026thinsp;=\u0026thinsp;O groups into the membrane backbone via integration of the rGO-I sheets into the IPN matrix. The hydrophilicity measurements from WCA values were further ascertained from the water uptake measurements. The uptake for the rGO-I@IPN_LC membranes was found to be nearly about 98%, which was 13% higher than that for neat IPN.\u003csup\u003e32\u003c/sup\u003e Also the roughness of the membrane surface increased owing to the LC sheet inclusion, which could be observed from the AFM images (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e). The RMS (Sq) roughness increased from 114.3 nm for neat IPN (PVDF/PDA) to 258.3 nm for the rGO-I@IPN_LC membrane (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ed,e). For the hydrophilic surface, with significant increment in roughness, the subsequent decrease in the WCA values establishes the validity of the Wenzel state, i.e., where the rough patches are fully filled with water, rather than the Cassie-Baxter state where the rough patches contain air. This increases surface wettability, thus directly impacting the ability of the membrane to form hydration layer and ward off unwanted foulants from its surface.\u003csup\u003e43\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eSurface charge, the second most important surface feature was evaluated using an Anton Paar Surpass Zeta Analyzer machine. The electrokinetic interactions occurring at the membrane-solute interface hint at the surface charge of the membranes which is calculated using the Helmholtz-Smoluchowski equation.\u003csup\u003e44\u003c/sup\u003e The zeta potential of the rGO-I dispersions was around \u0026minus;\u0026thinsp;30 mV owing to presence of polar hydroxyl, carboxyl, and secondary amines. Upon the impregnation of these sheets into the IPN matrix, the zeta potential of the rGO-I@IPN_LC membranes were found out to be around \u0026minus;\u0026thinsp;36 mV which was numerically nearly 16 mV more than that of neat IPN membrane. This significant rise can be ascribed to the increment in the polar groups from PVDF and polydopamine. However, when the membranes were triggered with basic pH, the zeta potential further rose to -42 mV giving rise to greater negative charge density on the surface. This phenomenon can be described by the zwitterionic nature of PDA whose isoelectric point is around 4. Upon shifting to a more basic pH, the -OH groups get converted to O\u003csup\u003e\u0026minus;\u003c/sup\u003e, thus generating negative charges on the surface and accounting invariably for the high surface charge (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb).\u003csup\u003e45\u003c/sup\u003e Thus, the presence of the rGO-I LC sheets augment the charge carrying capacity of the IPN membranes and creates a platform for successful charge based separation performance.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eShear aligned rGO-I LC sheets arrested by IPN\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThe most direct evidence of the retainment of the LC phase behaviour in the fabricated rGO-I@IPN_LC membranes was obtained from polarized optical microscope (POM) images. This LC phase suggests that the rGO-I sheets were arranged with long-range periodicity. The phase morphology of the IPN casting dope solution containing a range of different concentrations of rGO-I sheets in DMF along with the other IPN constituents was studied and gauged using POM (\u003cstrong\u003eFig.\u0026nbsp;5\u003c/strong\u003e). DMF was chosen as the solvent since all the constituents (PVDF and dopamine) were compatible and soluble in DMF. The neat IPN dope solution (only PVDF and dopamine) in DMF without the rGO-I sheets did not show the presence of any birefringence, which indicated that the LC phase in the rGO-I@IPN dope dispersion was primarily due to the presence of rGO-I nanosheets. To evaluate the phase behaviour of rGO-I@IPN dope dispersions, the concentration of rGO-I was varied from 1\u0026ndash;20 mg/mL (\u003cstrong\u003eFig.\u0026nbsp;5\u003c/strong\u003e and \u003cstrong\u003eS6\u003c/strong\u003e). Prominent birefringence with bright and dark brushes were found only after the concentration of the nanosheets exceeded 5 mg/mL and 7.5 mg/mL of rGO-I. Membranes fabricated with lesser rGO-I sheet concentrations (such as 1 mg/mL, 2.5 mg/mL, and 3 mg/mL) had significantly less sheets to show long range periodicity and the obtained membranes were non-uniform in nature. Thus such low concentrations were not taken forward.\u003c/p\u003e\n\u003cp\u003eAlthough rGO-I@IPN dope solutions did show nematic phase formation at a concentration of 5 mg/mL in DMF, and also demonstrated ordered alignments of the LC rGO-I sheets, yet the desalination performance (NaCl rejection\u0026thinsp;=\u0026thinsp;40%) was not satisfactory. Additionally, on increasing the concentration of rGO-I sheets in the IPN dope solution beyond 10 mg/mL, prominent birefringence was obtained, however the casted membranes were somewhat brittle which sacrificed their easy processability, and hence they were shelved. With all these observations in mind, we went ahead with dope solutions containing 7 mg/mL concentration of rGO-I sheets for our membrane fabrication. In the chosen concentration, i.e., 7.5 mg/mL, prominent birefringence was observed, and the stability of the obtained rGO-I@IPN dope solution was found to be extremely stable. Thus, the DMF containing dope solution of rGO-I@IPN with 7.5 mg/mL sheet concentration was taken forward and the exhibited well-recognized birefringence between the polarizers was direct evidence of the formation of lyotropic LC phase. Achieving such rGO-I LC would provide unique prospects for fabricating well-aligned, ordered, and novel rGO-I@IPN LC-based mixed matrix membranes.\u003c/p\u003e\n\u003cp\u003eTo further the understanding of the LC phase formation and study the structural improvements obtained via formation of the ordered phases, Small-Angle X-Ray Scattering (SAXS) was performed (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea,b). Precisely, the scattering factor ranges, q (q\u0026thinsp;=\u0026thinsp;2\u0026pi;/d\u0026thinsp;=\u0026thinsp;4\u0026pi; sin \u0026theta;/\u0026lambda;) were employed to evaluate the structural advancements of rGO-I dispersions and the rGO-I@IPN_LC membrane. The required information pertaining to the structure of the rGO-I dispersion and the rGO-I@IPN_LC membrane was obtained from the Lorentz Correction Kratky plot (I*q\u003csup\u003e2\u003c/sup\u003e vs. q). From the Kratky plots at the chosen concentration of 7.5 mg/mL of the rGO-I sheets, crystal clear diffusive patterns and broad range scattering peaks were obtained at q\u003csub\u003enem\u003c/sub\u003e= 0.056 and 0.074 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e, which suggested the presence of a high-order nematic phase. After confirmation of the nematic phase in the dispersion, the SAXS experiment was repeated for the rGO-I@IPN_LC membrane, and the scattering image (\u003cstrong\u003eFig. S7\u003c/strong\u003e) was reported. From the scattering image, less intense broad peaks were detected at 0.42 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e and 0.50 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e, which further ascertained the retainment of the nematic phase of rGO-I in the final membrane. Along with the nematic phases, the shear alignment achieved while casting the rGO-I@IPN_LC membrane, led to the appearance of two additional peaks near 0.106 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e and 0.116 \u0026Aring;\u003csup\u003e\u0026minus;1\u003c/sup\u003e indicating the existence of lamellar phase. Thus, it can be rightfully concluded that the presence of the high-order nematic and lamellar phases in the rGO-I@IPN_LC membrane was only due to the addition of the rGO-I nanosheets and IPN further arrested this phase in the membrane.\u003csup\u003e46,47\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eNow, to identify the viscoelastic phase behaviour of the rGO-I@IPN dope solutions rheological studies were performed which were very crucial in this study. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec displays the variation of complex viscosity as a function of shear rate for different concentrations of rGO-I nanosheets in the IPN dope solution. In general, is it the behaviour of the fluid that decides its nature (i.e. Newtonian and non-Newtonian (shear thinning)). Here, the concentration of the rGO-I (ϕ) nanosheets played a major role in deciding the nature and the behaviour of the dope solution. From the plot, a pseudoplastic shear-thinning behaviour was obtained at various concentrations of the rGO-I nanosheets. The reduced complex viscosity of the rGO-I@IPN solutions with increased shear rates was in accordance with earlier reports. At low shear rates, the nematic phases in the GO-ICM@IPN dispersion were seen to be distributed randomly and they did not align, which resulted in higher viscosity. However, at high shear rates, the randomly distributed rGO-I sheets, demonstrating nematic phases were found to perfectly align in the direction of shear stress. This in turn produced less physical interaction and thus decreased the complex viscosity.\u003c/p\u003e\n\u003cp\u003eThe viscosity of rGO-I@IPN solutions depended on the rGO-I content and molecular arrangements. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ed shows the plot of zero shear viscosity as a function of rGO-I concentration (ϕ) at shear rates of 0.1 s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. At a low concentration (ϕ\u0026thinsp;=\u0026thinsp;0.25 mg/mL), rGO-I@IPN dispersion in DMF was found to exhibit an isotropic phase post which the viscosity increased up to a specific concentration ϕ\u003csub\u003ec\u003c/sub\u003e ca. 1mg/mL and attained a maxima. Upon further increasing the rGO-I concentration in the IPN dope solution a steady decrement in the complex viscosity was obtained which reached a minima and subsequently started increasing.\u003c/p\u003e\n\u003cp\u003eA probable explanation for the decline in zero shear viscosity could be due to the formation of a less-viscous nematic liquid crystalline phase of rGO-I. The isotropic to the nematic phase transition was observed when the rGO-I nanosheet content in the IPN dope solution ranged between maxima and minima, while in zero shear viscosity condition. An isotropic to nematic phase change was observed at a concentration range from 1-2.5 mg/mL.\u003c/p\u003e\n\u003cp\u003eHerein, ordered nematic phase was obtained after ϕ\u003csub\u003ec\u003c/sub\u003e reached the concentration of 2.5mg/mL of rGO-I nanosheets in the IPN dope solution. The complex viscosity of the rGO-I@IPN dope solutions were found to exhibit decent agreement with the viscosity power law model in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec. Usually, the exponents for ideal plastic material is about \u0026minus;\u0026thinsp;1 (power law model), which reduced from \u0026minus;\u0026thinsp;0.4165 to \u0026minus;\u0026thinsp;0.6898 by increasing rGO-I concentration from 0.25 to 7.5 mg mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, confirming the enhanced plasticity originating from the order nematic rGO-I phases.\u003csup\u003e23,48,49\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eWater transport properties and dynamic antifouling studies\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA thin, robust, and selective membrane is supposed to yield the most favourable filtration performance. The presence of liquid-crystal rGO-I nanomaterials soldered inside the IPN membrane matrix, creates a platform for the fabrication of promising systems enabled with enhanced water permeation and superior rejection properties.\u003c/p\u003e\n\u003cp\u003eEvaluation of pure water flux is an important criterion for water remediation systems since it is very difficult to hit the age-old trade-off between selectivity and permittivity of membranes. The pure water flux values were evaluated in the pressure range of 10 to 100 psi (\u003cstrong\u003eFig. S8\u003c/strong\u003e). The rGO-I@IPN_LC membranes exhibited linearity in the flux values upon steady increment in the transmembrane pressure (85 LMH at 25 psi, 105 LMH at 50 psi, 120 LMH at 75 psi, and 145 LMH at 100 psi). The flux values fall within the range of ultrafiltration to nanofiltration range. This linear increment is probably due to changes in pore architecture which is often brought about by the variation in transmembrane pressure. Additionally, the data is in accordance with the Hagen\u0026ndash;Poiseuille (HP) model for laminar membranes. However, when compared to the neat IPN membranes (900 LMH at 50 psi), the rGO-I@IPN_LC membranes showcase a much lower flux value which can be due to the pore tightening feature brought about by the large aspect ratio rGO-I sheets inside the IPN matrix. These sheets fill in the pore volumes and result in effective pore size reduction. The distribution of the sheets is facilitated by the fact that the rGO-I sheets are electrostatically bound to the dopamine moieties of the IPN membrane which upon sequential in-situ polymerization makes these sheets available to the system. Additionally, the enhanced water permeation of the fabricated membranes can also be attributed to the presence of the functionalized and partially reduced GO sheets (i.e. rGO-I sheets) where there is an inherent reduction in the density of oxygen containing moieties (as compared to neat GO) which in turn helps in frictionless water transport via slip flow mechanism through the ordered channels of the rGO-I sheets present inside the IPN matrix.\u003csup\u003e50\u003c/sup\u003e The water transport via these membranes is effectively due to a combination of pores and narrowed nano channels of the aligned rGO-I LC sheets.\u003c/p\u003e\n\u003cp\u003eThe flux experiments were continued for a period of 3 weeks for testing the long-term stability of the fabricated membranes under high transmembrane pressure (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ea). It was observed that the change in flux values throughout the duration of the operation was quite negligible, thus establishing the long-term stable performance of the membrane. FTIR and XPS studies (\u003cstrong\u003eFig S9, S10\u003c/strong\u003e) were also performed to check the effect of such long-term performance on the inherent environment of the membrane. No change was observed in the chemical environment and functionalities of the membrane.\u003c/p\u003e\n\u003cp\u003eAfter completion of the pure water flux experiments, the pure water feed was replaced by a feed solution of Bovine Serum Albumin (BSA) for gauging the antifouling abilities of the synthesized membranes (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eb). For a membrane to qualify as antifouling, the membrane surface after being exposed to a bio foulant (here BSA) should quickly recover its initial performance after getting rid of the foulant via backflushing. Thus the flux recovery or retention should be very high for asserting its fouling-resistant nature. It was observed that the flux recovery ratio of the rGO-I@IPN_LC membranes was nearly 98%, which is much higher than the neat IPN membranes (85%).\u003csup\u003e51\u003c/sup\u003e In general, negatively charged membranes naturally repel co-charged foulants via electrostatic repulsion. The rGO-I@IPN_LC membranes being negatively charged (evidenced from the zeta potential values) are efficient enough to repel the BSA molecules from adhering onto the surface due to their high surface roughness and hydrophilicity. The high hydrophilicity subsequently leads to the formation of an impermeable hydration layer which further strengthens the repulsion of the BSA molecules.\u003csup\u003e52\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePrecise molecular sieving in IPN-arrested rGO-I LC sheets\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThe presence of positively charged Dopamine.HCl helped in binding the counter charged rGO-I sheets electrostatically to itself and upon sequential polymerization of dopamine-anchored rGO-I, a jammed network consisting of PVDF, and liquid crystal rGO-I anchored PDA (polydopamine) was obtained. Thus, the existence of the IPN was instrumental towards further triggering and arresting the alignment of the rGO-I LC sheets and also helped in controlling the d-spacing of the sheets (~\u0026thinsp;6 \u0026Aring;) without the need of external crosslinking. The effectiveness of such a IPN aligned structure can be understood from the ion transport properties of the membrane.\u003c/p\u003e\n\u003cp\u003eWith reasonably high water flux values, the membranes (rGO-I@IPN_LC[\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e] and rGO-I@IPN_LC[7.5]) were subjected to salt rejection studies. 2000 ppm of monovalent (NaCl) and divalent (Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e and MgSO\u003csub\u003e4\u003c/sub\u003e) salts were taken as feed and the removal efficiency was evaluated at regular intervals using a TDS meter (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ec). The membranes with 7.5 mg/mL concentration of rGO-I sheets, rejected nearly 97% of NaCl for a continuous period of 21 days after which the percent rejection decreased negligibly (~\u0026thinsp;95.6%). The negatively charged membrane surface and pores can effectively repel the co-charged Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e ions and the rejection of the Na\u003csup\u003e+\u003c/sup\u003e can be explained from the cation-\u0026pi; interactions occurring between the monovalent ion and the sp\u003csup\u003e2\u003c/sup\u003e hybridised structures of rGO-I sheets.\u003csup\u003e16,53\u003c/sup\u003e After a period of 21 days it was observed that the zeta potential of the membranes reduced a bit (initial value = -36 mV, after 21 days of NaCl rejection = -33 mV) and the EDAX spectra of membrane hinted at the presence of Na\u003csup\u003e+\u003c/sup\u003e ions (\u003cstrong\u003eFig. S11c\u003c/strong\u003e), which could further explain the insignificant decrement in salt rejection incurred after 3 weeks of continuous operational cycles. However, the membrane with no LC phase, i.e. the membrane with 1 mg/mL of rGO-I sheets were found to reject only 25% of NaCl salt. This observation strengthens the fact that the formation of LC phases contributes greatly to effective ion rejection owing to the highly oriented architecture and thus justifies the rationale behind taking forward only the membrane with 7.5 mg/mL concentration for further studies.\u003c/p\u003e\n\u003cp\u003eThe salt removal efficiencies were also tested with divalent salts (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ed) and it was observed that for both Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e and MgSO\u003csub\u003e4\u003c/sub\u003e, the rejection efficacy reached nearly 99% owing to the larger hydrodynamic radii of the concerned ions. Intrinsically speaking, high-valence SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e undergoes greater repulsion via the membrane surface and pores than Cl-, while low-valence Na\u003csup\u003e+\u003c/sup\u003e faces higher electrostatic attraction as compared to Mg\u003csup\u003e2+\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eIn general, a possible overall mechanism behind such rejection efficiencies stems from a host of factors including reduced pore size, narrowed d-spacing and strong electrostatic interactions (high negative charge on membrane surface from zeta potential values). In the rGO-I@IPN_LC membranes the negatively charged groups and the size-reduced pore walls retain the counter-charged ions and repel the co-ions via the Donnan exclusion principle and size sieving mechanisms. This is necessary in order to maintain charge neutrality on either side of the membrane. Besides, the ordered nanochannels with reduced interlayer-spacing of the rGO-I LC sheets present inside the matrix also augments the ion rejection efficiency.\u003c/p\u003e\n\u003cp\u003eFor further investigating and exploring the charge-based rejection ability of the LC membranes, the membrane surface charge was triggered by altering the pH of the membrane environment. PDA being zwitterionic in nature is deemed to be capable of varying the nature of surface charge based on pH. The membrane was thus endowed with negative charges with basic pH since the -OH groups present in the PDA structure are quantitatively much more in number than that of -NH, accounting for higher negative charge density.\u003csup\u003e32\u003c/sup\u003e After pH variation, the surface exhibited a negative charge density of -42mV and the NaCl rejection efficiency rose to 99.8% and the results remained consistent for the entire duration of 21 days (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ed). This result corroborates the fact that more the surface charge density, more is the efficacy demonstrated towards resisting the monovalent ion transport.\u003c/p\u003e\n\u003cp\u003eTo further substantiate the ion and dye nanofiltration performance a host of cationic and anionic dyes and antibiotics were taken as model foulants. Separation mechanisms can have synergistic contributing factors including Donnan exclusion, size sieving mechanism (pore size and narrow interlayered channels), and complex formation. Intrinsic features such as surface charge, hydrophilicity of the surface and a range of other operational conditions also affect the removal performance. The presence of rGO-I LC sheets not only leads to pore size reduction owing to their aspect ratio but also provides negative charge carrying centres which augments the surface charge of the fabricated membranes. The membranes were able to reject nearly 97% of the anionic dye CR and the rejection improved to 99% for the cationic MB dye (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ee). MB being cationic in nature experiences high electrostatic attraction to the negatively charged membrane and gets strongly adsorbed to the membrane surface (evidenced from its elemental footprint in EDAX spectra). The anionic dye on the other hand faces repulsion being co-charged and steric hindrance also accounts for its rejection. However, its elemental footprint is not exhibited in the EDAX spectra which further verifies the repulsion hypothesis. Mixture of dyes involving MB and CR were also taken for dye rejection studies. As evidenced from the UV-Vis spectra the signature peaks corresponding to the dyes were strategically absent in the membranes could be cleaned easily via backflushing and could reject nearly 15 cycles of the dyes with no significant deterioration in the rejection efficiency (\u003cstrong\u003eFig.\u0026nbsp;12c,d,e\u003c/strong\u003e). The rejection performance was further corroborated using another set of cationic, Safranin O and an anionic, AB dye (\u003cstrong\u003eFig. S12g\u003c/strong\u003e). Here too similar trends in rejection efficacy were obtained.\u003c/p\u003e\n\u003cp\u003eSimilar observations were made during antibiotic removal experiments. The negatively charged amoxicillin got heavily repulsed by the negatively charged membrane and recorded a rejection of about 97%. For the neutral azithromycin antibiotic, the reduced pores of the membrane and the narrowed interlayer spacing of the rGO-I LC sheets worked in tandem to yield a rejection percentage of 98% (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ef).\u003c/p\u003e\n\u003cp\u003eIn order to gauge the performance and durability of the membranes, we investigated their chlorine tolerance properties. Most of the commercial membranes are attacked by the chlorine present in water which in turn deteriorates its intrinsic properties and separation performance. In brief, the membranes are exposed to strong concentrations of sodium hypochlorite solutions and are again subjected to NaCl rejection experiments. The lesser the deviation in the rejection values, more resistant is the designed membrane towards chlorine attack. The rGO-I@IPN_LC membranes demonstrated just a 3\u0026ndash;5% reduction (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ed) in the salt rejection values after being exposed to chlorine. In all probability, such superior chlorine tolerance arises from the fact that the free chlorines get trapped via the primary and secondary amines of polydopamine which in turn restricts amide formation. Thus, chlorine attack fails to impede the membrane performance or adversely affect its intrinsic architecture. The 3\u0026ndash;5% decline results from the inevitable attacks made by the free chlorine atoms on the -NH groups of the rGO-I LC sheets.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRisk assessment and antimicrobial properties\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThe antibacterial performance of the fabricated rGO-I@IPN_LC membranes was effectively gauged from the standard plate count method. Both \u003cem\u003eS. aureus\u003c/em\u003e and \u003cem\u003eE. coli\u003c/em\u003e were used as the model bacterial strains for carrying out the evaluations. In general, wastewater contaminated with bacterial microorganisms can pose serious health hazards upon entering the ecosystem. Thus, removing them from the wastewater resources poses to be a major research concern. For the fabricated membrane, a 3-log reduction (percent reduction\u0026thinsp;~\u0026thinsp;99.8) was observed for the gram-positive bacterial strain, i.e., \u003cem\u003eS. aureus\u003c/em\u003e, and a 2-log reduction (percent reduction\u0026thinsp;~\u0026thinsp;99.54) was obtained for \u003cem\u003eE. coli\u003c/em\u003e, the gram-negative strain. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003ea,b demonstrates the digital images for both the bacterial colonies formed in the TSA plates in the neat IPN, the control samples, and rGO-I@IPN_LC membranes. Here the presence of the functionalized GO is primarily responsible for such superior bacterial response. GO is widely known for its antibacterial activities due to sharp edges\u003csup\u003e54\u003c/sup\u003e (which physically disrupts the cell membrane of the bacteria) and its ability to generate huge amounts of oxidative stress via apoptotic mechanisms.\u003csup\u003e55,56\u003c/sup\u003e The fabricated membrane is incorporated with partially reduced functionalized GO which did not hamper its lateral dimension and oxygen functional groups much (as evidenced from the AFM images (\u003cstrong\u003eFig. S3\u003c/strong\u003e and FTIR spectra). Thus, these nanomaterials present in the IPN matrix were solely responsible for inhibiting bacterial growth based on the similar mechanisms mentioned above for GO. However, it was observed that the inhibition of bacterial growth was higher for \u003cem\u003eS. aureus\u003c/em\u003e as compared to \u003cem\u003eE. coli.\u003c/em\u003e A plausible mechanism for this observation lies in the fact that the synthesized nanoparticles, rGO-I being negatively charged strongly interferes with the bacterial lipid polysaccharide membrane of the positively charged S. aureus, thus producing significantly high amounts of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e which damages the S. aureus membrane.\u003csup\u003e57\u003c/sup\u003e However, E. coli possess negative lipopolysaccharides on its exterior and hence its permeability towards the rGO-I moieties is comparatively a bit lesser, which explains for its lesser log reduction.\u003csup\u003e58\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eIn addition to the antibacterial performance, the membranes were also tested for in-vitro cyctotoxcity. This feature of the rGO-I@IPN_LC membranes were evaluated using the standard MTT assay protocol. In general, GO is cytotoxic in nature. Studies usually suggest that on reducing the lateral size of the sheets, cytotoxicity decreases. Here, L929 mammalian cell lines were subjected to this test evaluation. As per the test standards, cytotoxic potential of the evaluated material increases with decrease in cell viability as calculated from the optical density measurements. If the neat sample (i.e., 100% extract) has a cell viability of lesser than 70% then the material is deemed to be cytotoxic. However, the rGO-I@IPN_LC membrane exhibited a cell viability of nearly 73% for the 100% test sample and the viability increased linearly with decrease in the extract percentage, reaching a maximum of 90% for the 10% test sample (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003ec). Thus, the fabricated samples could be claimed as non-toxic or cytocompatible towards mammalian cells, which is an important prerogative for water remediation systems. Additionally, from the long-term leaching studies (UV-Vis spectroscopy of the water permeate generated after long-term operation, \u003cstrong\u003eFig. S12h\u003c/strong\u003e), it was found that the fabricated rGO-I sheets did not escape into the permeate. This non-leaching behaviour arises from the fact that the nanosheets are not exposed to the environment, rather the IPN matrix protects the rGO-I LC sheets inside its matrix and prevents any further leaching. This evidence further establishes the cytocompatible nature of the fabricated rGO-I@IPN-LC membranes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFundamental understanding of the membrane performance using MD simulations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe employed all-atomistic MD simulations to understand the mechanisms governing the superior separation performance of the rGO-I@IPN-LC membranes. The membranes studied include an IPN membrane comprising PVDF and polydopamine chains but without rGO-I, as well as two variations of the rGO-I@IPN membrane: rGO-I@IPN[\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e] with a lower rGO-I concentration (number of rGO-I layers considered 3) and rGO-I@IPN[7.5] with a higher rGO-I concentration(number of rGO-I layers considered 6). In the lattermost scenario, the rGO-I exhibits extensive ordering, indicative of LC behaviour with well-defined nematic phases having an interlayer spacing of 0.62 nm. A cartoon illustrated in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ea describes schematically as to how the feed side saltwater solution and the permeate side freshwater solution are separated by the LC membrane. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003eb shows the number of water molecules permeating through the different membranes (IPN, rGO-I@IPN[\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e], rGO-I@IPN[7.5]) as a function of simulation time under a feed-side pressure of 100 MPa for a NaCl salt solution. Therein, one can see that the number of water molecules permeated across the membrane scales linearly with time, implying that a roughly constant chemical potential and pressure gradient is maintained in the simulations over time. As seen in the experiments, the MD simulations support that the water flux is reduced upon impregnation of the IPN membrane with rGO-I, with a higher reduction in water permeability at a higher rGO-I concentration. A comparison of Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003eb and Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ec shows that the water permeability is similar for NaCl and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e aqueous solution, indicating that the water transport occurs independently of ion transport.\u003c/p\u003e\n\u003cp\u003eWe also report the water permeance and salt rejection for NaCl and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e salt solutions with different membranes, in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ed and Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e. The water permeability is defined as the volume of water permeated per unit time, membrane area, and pressure. Similarly, the percentage of salt rejection is defined as \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\left(1-\\frac{\\text{T}\\text{o}\\text{t}\\text{a}\\text{l} \\text{n}\\text{u}\\text{m}\\text{b}\\text{e}\\text{r} \\text{o}\\text{f} \\text{i}\\text{o}\\text{n}\\text{s} \\text{i}\\text{n} \\text{p}\\text{e}\\text{r}\\text{m}\\text{e}\\text{a}\\text{t}\\text{e} \\text{s}\\text{i}\\text{d}\\text{e} \\text{a}\\text{t} \\text{t}\\text{i}\\text{m}\\text{e} t}{\\text{T}\\text{o}\\text{t}\\text{a}\\text{l} \\text{n}\\text{u}\\text{m}\\text{b}\\text{e}\\text{r} \\text{o}\\text{f} \\text{i}\\text{o}\\text{n}\\text{s} \\text{i}\\text{n} \\text{f}\\text{e}\\text{e}\\text{d} \\text{s}\\text{i}\\text{d}\\text{e} \\text{a}\\text{t} \\text{t}\\text{i}\\text{m}\\text{e} \\text{t}=0 }\\right)\\times 100\\)\u003c/span\u003e\u003c/span\u003e, where \u003cem\u003et\u003c/em\u003e is the simulation run time, and the total number of ions is defined as the sum of the numbers of positive and negative ions.\u003c/p\u003e\n\u003cp\u003eNotably, as seen in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ed the MD simulation results are within 25% of the experimental water permeance, which indicates that the proposed all-atomistic model of the membrane can capture the physics of water and ion transport, as well as the chemistry of the rGO-IPN membranes. Moreover, as seen in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e, our simulations demonstrate a 100% salt rejection for NaCl and Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e salt solutions, even after an 85 ns simulation period, wherein no ions are able to reach the permeate region. This remarkable result is attributed to the high barrier that impedes ion passage across the membranes. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e vividly illustrates that the majority of ions remain within the feed region, while a few do enter the membrane, although none of the Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, and SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e ions reach the permeate side. Furthermore, our simulations also reveal that an increase in the concentration of rGO-I sheets integrated within the IPN (PVDF and PDA chains) membranes leads to a reduction in the number of ions residing within the membrane region, favouring retention within the feed region. Interestingly, we found that chloride ions pass more frequently from the feed region to the membrane region compared to sodium ions for NaCl salt solution. This trend is clearly depicted in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e, wherein, initially, the feed region contains 18 Na\u003csup\u003e+\u003c/sup\u003e and 18 Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e ions for the NaCl salt solution, while for the Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e salt solution, there are 16 Na\u003csup\u003e+\u003c/sup\u003e ions and 8 SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e ions maintaining the same molarity in both cases. Overall, our simulation framework develops a comprehensive model for rGO-I@IPN membranes and provides molecular-level insights into ion permeation and salt rejection via them.\u003c/p\u003e"},{"header":"3. DISCUSSION","content":"\u003cp\u003eA GO sheet is characterized mainly by oxidized and non-oxidized domains and very scantly via holes.\u003csup\u003e59\u003c/sup\u003e The non-oxidized domains contribute to the formation of specific percolating regions and contribute to efficient water permeation and ion selectivity. Herein we establish partially reduced rGO-I sheets via feasible chemical interactions and form stable mixed matrix membranes where lyotropic liquid crystalline rGO-I sheets were electrostatically anchored to IPN matrix and the LC behaviour was retained even in the mixed matrix system. The electrostatic interactions, π-π interactions and the hydrogen bonds formed between the IPN, and the rGO-I sheets helped in further arresting the shear aligned rGO-I sheets. Thus, the membranes exhibited the existence of nematic phases. The retainment of LC behaviour effectively offers a pathway to long-range order and can be attributed to the orientational property of the LC sheets which was triggered by the nano confinement of IPN. \u003csup\u003e60\u0026ndash;62\u003c/sup\u003e The IPN also helped in protecting the sheets from swelling and preserved their narrow interlayer spacing. Leaching of the nanosheets also gets restricted via the mixed matrix IPN strategy.\u003csup\u003e63\u003c/sup\u003e Such highly ordered membrane matrix shows stable water permeation and ion sieving for long operational periods and can be easily reused via backflushing with DI water over several operational cycles. Additionally, our comprehensive MD simulations reveal the mechanism of ion rejection by the rGO-I@IPN membranes to be the inability of most ions to enter the membranes and the the prevention of the ions that do enter to exit the membrane.\u003c/p\u003e"},{"header":"4. CONCLUSION","content":"\u003cp\u003eA novel and lyotropic liquid crystal enabled IPN membrane was reported by in-situ electrostatic attachment of rGO-I LC sheets in a IPN polymeric matrix composed of PVDF and PDA. The rGO-I sheets were obtained via a facile, practicable, and mild green-tea reduction methodology. Interestingly the LC structure of the rGO-I sheets were maintained even after membrane fabrication which aided membrane stability and performance. The fabricated membranes were chemically, thermally and mechanically quite resilient, owing to the interpenetrated structure. The reported procedure offers the coalescence of several distinctive traits that are imperative for sustainable water remediation. The membranes were characterised by stable long-term water flux (145 LMH) under high transmembrane pressure, and enhanced separation performance in terms of dye (\u0026gt;\u0026thinsp;98%), salt (97%) and antibiotic (98%) rejection. The strong chlorine resistance and antifouling characteristics further demonstrated the usability of these membranes. The membranes also demonstrated quick bacterial reduction capabilities for both gram negative (\u003cem\u003eE. coli\u003c/em\u003e, 2-log reduction) and gram-positive (\u003cem\u003eS. aureus\u003c/em\u003e, 3-log reduction). The cytocompatible behaviour of the membranes against mammalian cell lines, place them in the safe category of risk assessment while being disposed of in a landfill. In general, the existing state-of-the-art RO membranes are devoid of bactericidal properties, essentially requires UV pre-treatment and prefiltration steps with an antiscalant in the feed for mitigating fouling. However, our mixed matrix IPN approach can mark the arrival of sustainable antiscalant free antifouling membranes for water remediation and has the potential for large scale deployment, thus providing sustainable and guaranteed water supply for the generations to come.\u003c/p\u003e"},{"header":"5. EXPERIMENTAL SECTION","content":"\u003cp\u003e \u003cb\u003eMaterials and Methods\u003c/b\u003e:\u003c/p\u003e \u003cp\u003ePolyvinylidene fluoride (PVDF (Kynar 761 grade, Mw\u0026thinsp;=\u0026thinsp;440,000 g/mol) was obtained from Arkema. Graphene oxide (GO) was procured from Nanomatrix Materials (Rajasthan), India. Sigma Aldrich provided 2-isocynatoethyl methacrylate (ICM), dibutyltin dilaurate (DBTDL), N,N-methylene bisacrylamide, dopamine hydrochloride (DA, 99%), and sodium periodate (NaIO\u003csub\u003e4\u003c/sub\u003e, \u0026ge;\u0026thinsp;99.8%). Tris(hydroxymethyl)aminomethane (Tris, 99.8\u0026ndash;100%) was purchased from Sisco Research Laboratories Pvt. Ltd. N, N-dimethylformamide (DMF, 99.0%), dimethylacetamide (DMAc, 99%) sodium hypochlorite, and sodium hydroxide pellets (NaOH, 97.0%) were acquired from SD Fine Chemicals Ltd. Methylene blue (MB, 319.85 Da), Congo red (CR, 696.665 Da), amido black 10B (AB, 595.5 Da), safranin O (SO, 350.85 Da) dyes, green tea, and dry acetone were obtained from a local vendor. Giemsa stain (GS 291.8 Da), Sudan IV (SD 380.44 Da), tetracycline (TC 444.43 Da), oxytetracycline (OTC 460.46 Da), azithromycin (Azithro, 785 Da), amoxicillin (365.4 Da), and vitamin B\u003csub\u003e12\u003c/sub\u003e (VB 1355.37 Da) were obtained from SRL Chemicals. All the chemicals and obtained materials were used without further processing and purification.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of rGO-I\u003c/b\u003e:\u003c/p\u003e \u003cp\u003eThe obtained GO was modified\u003csup\u003e64\u003c/sup\u003e using 2-isocynatoethyl methacrylate kept in dry acetone in the presence of nitrogen atmosphere. In essence, GO was effectively dispersed in dry acetone and was bath sonicated for 30 minutes. Subsequently, 2-isocynatoethyl methacrylate was incorporated into the system dropwise. The reaction mixture was stirred for 24 hours at room temperature under a nitrogen atmosphere in presence of a DBTDL catalyst. Upon completion of 24 h, the product was washed and centrifuged using THF and was then vacuum dried at 60\u0026deg;C. The modified GO was termed \u003cem\u003eGO-I\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eTo reduce the GO-I particles obtained in the previous step, reduction was carried out using green tea extract. The extract was prepared using 2 g of market-available green tea. It was mixed with 50 mL of distilled water at 70\u0026deg;C for 30 min. The extract was obtained by isolating the tea leaves and was stored in the refrigerator for further use. For the reduction step, the extract (10 mL) was added dropwise to a 40 mL aqueous suspension of the modified GO (10 mg/mL) for 45 min. Subsequently, the mixture was refluxed for 6 h at 60\u0026deg;C. Finally, the product was isolated by centrifugation at 8000 rpm for 15 min. It was then washed with DI water four times and dried overnight in an oven at 70\u0026deg;C. The obtained product was termed as r\u003cem\u003eGO-I\u003c/em\u003e.\u003c/p\u003e \u003cp\u003e \u003cb\u003eFabrication of rGO-I LC-anchored IPN membrane\u003c/b\u003e:\u003c/p\u003e \u003cp\u003e30 wt% of membrane casting solution (dope solution) was prepared in DMF (7 mL) using PVDF and dopamine.HCl monomer in a 2:1 ratio. At an elevated temperature of about 80 \u003csup\u003e\u0026ordm;\u003c/sup\u003eC, the components were stirred continuously until a consistent bubble-less solution was obtained. To this, different amounts of rGO-I (10 mg, 75 mg, and 200 mg) in DMF (3 mL) were added. The solution was stirred in a hot plate until a homogeneous and uniformly mixed dope solution (1 mg/mL, 7.5 mg/mL, and 20 mg/mL, respectively) was obtained.\u003c/p\u003e \u003cp\u003eSubsequently, to realize the casting of the membranes, a 300 \u0026micro;m doctor blade was taken, and a speed of 7\u0026ndash;8 cm/s was set in an automatic film applicator for casting the membranes onto a glass plate. The membranes were then precipitated in a cold (ca. 4 \u0026ordm;C) aqueous coagulation bath containing 10 mM of tris buffer (pH\u0026thinsp;=\u0026thinsp;8.5) and 5 mM of NaIO\u003csub\u003e4\u003c/sub\u003e. The precipitated membranes were kept in the cold buffer solution for 7 days. This was done in accordance with previous optimized studies for maximum reduction in pore size.\u003csup\u003e32\u003c/sup\u003e The fabricated membranes were then thoroughly washed and rinsed with ultrapure water before any assessments were carried out. The fabricated membranes were termed \u003cem\u003erGO-I@IPN_LC\u003c/em\u003e (\u003cem\u003erGO-I@IPN_LC\u003c/em\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], \u003cem\u003erGO-I@IPN_LC[7.5]\u003c/em\u003e, and \u003cem\u003erGO-I@IPN_LC\u003c/em\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]) membranes. The rGO-I@IPN_LC[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] membrane exhibited a very uneven surface and was scrambled up due to high dosage of \u003cem\u003egGO-I\u003c/em\u003e; hence this particular concentration was not taken forward. The rGO-I@IPN_LC[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] membrane dope solution did not show the presence of any prominent birefringence (which is typical characterization of LC behaviour), and consequently, this membrane proved ineffective in achieving efficient rejection performance. Here, the rGO-I@IPN_LC membrane refers to the membrane with 7.5 mg/mL concentration of rGO-I sheets. \u003cb\u003eScheme 1\u003c/b\u003e illustrates the chemical reaction involved during the synthesis of the rGO-I sheets and subsequently the design of the rGO-I@IPN_LC membrane.\u003c/p\u003e \u003cp\u003e \u003cb\u003eScheme 1.\u003c/b\u003e Chemical reaction involved in the synthesis of rGO-I particles and subsequent fabrication of the rGO-I@IPN_LC membrane via the non-solvent induced phase separation technique.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSynthesis of charge-triggered membranes via pH variation\u003c/b\u003e:\u003c/p\u003e \u003cp\u003eMembrane charges were triggered by tuning the pH of the membrane environment. The fabricated membranes were dipped either in 1 N HCl or 1 M NaOH (depending upon the requirement) for a period of 24 hours at room temperature. Before using the membranes, they were washed thoroughly with DI water.\u003c/p\u003e \u003cp\u003e \u003cb\u003eComputational modelling and simulation details\u003c/b\u003e:\u003c/p\u003e \u003cp\u003eWe used classical molecular dynamics (MD) simulations to examine the desalination performance of the IPN-based GO LC membranes for two different salt solutions (i.e., NaCl and Na2SO4). The system consisted of the membrane, saltwater on the feed side, and freshwater on the permeate side, with a simulation box length of 24 nm in the z direction (perpendicular to the membrane) and a cross-sectional area of 5.2 \u0026times; 5.2 nm2 in the xy plane (parallel to the membrane), as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e9\u003c/span\u003ea. For the feed-side region of the simulation box, we included 5000 water molecules, 18 Na\u0026thinsp;+\u0026thinsp;ions, and 18 Cl- ions, resulting in a molar concentration of aqueous salt solution of 0.2 mol/L (~\u0026thinsp;11.7 g/L). On the permeate (pure water) side, we added 3000 water molecules. We used the open-source GROningen MAchine for Chemical Simulations (GROMACS) package for carrying out the MD simulations. The simulation timestep was taken as 1 fs and simulations were run for ~\u0026thinsp;90 ns. During the simulations, we employed a cutoff distance of 12.0 \u0026Aring; for the Lennard-Jones (LJ) interactions, while long-range electrostatic interactions were calculated using the Particle-Mesh-Ewald (PME) method. After setting up the simulation box, energy minimization was performed using the steepest descent method with a maximum step size of 0.01 \u0026Aring; and a force tolerance of 10 kJ mol\u0026thinsp;\u0026minus;\u0026thinsp;1 nm\u0026thinsp;\u0026minus;\u0026thinsp;1, and subsequently the system was brought to equilibrium in the canonical ensemble (maintained at constant NVT, where N represents the number of atoms, V the volume of the system, and T the absolute temperature of the reservoir), while maintaining the permeate and feed side pistons both at atmospheric pressure (1 atm) for 4 ns. To apply the desired pressure (1 atm) on the piston atoms, we froze the atoms in the piston group in x and y directions and then applied a constant force pulling on the centers of mass of both the pistons, containing 1008 atoms each (in opposite directions) with a total force equal to 1.68156 kJ/mol nm. During the simulations, the system was coupled to a global thermostat using Langevin dynamics with a damping factor of 5.0 ps-1. Finally, the non-equilibrium MD simulations were conducted using the NVT ensemble with a uniform pressure (P), i.e., 100 MPa, applied on the feed-side piston along the flow direction (+\u0026thinsp;z), while atmospheric pressure (1 atm) was applied to the permeate-side piston opposite to the flow direction (\u0026ndash;z). Periodic boundary conditions were applied along all three directions (x, y, and z). The number of water molecules and ionic species moving from the feed to the permeate side were monitored over time to determine the water flux and the ion rejection.\u003c/p\u003e \u003cp\u003e \u003cb\u003eConstruction and setup of the rGO-I@IPN_LC membrane and desalination system and details on the force-field parameters\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe appropriate selection of force-field parameters is essential for ensuring the accuracy of classical MD simulations. In this work, the LJ and Coulombic interatomic parameters provided by Zeron et al. were employed for the Na\u003csup\u003e+\u003c/sup\u003e, Cl\u003csup\u003e\u0026minus;\u003c/sup\u003e, and SO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e ions\u003csup\u003e65\u003c/sup\u003e, while Cheng et al.\u0026rsquo;s parameters were used for the carbon atoms (only the LJ parameters as carbon atoms have no partial charges)\u003csup\u003e66\u003c/sup\u003e. Water molecules were represented using the four-site TIP4P/2005 model.\u003csup\u003e67\u003c/sup\u003e The all-atom optimized potentials for liquid simulations (OPLS/AA) force-field parameters were used for the atoms in the PVDF and PDA chains, as well as in the rGO-I sheets, as generated using PolyParGen.\u003csup\u003e68\u003c/sup\u003e The .gro files of PVDF with 6 monomeric units and PDA with 4 monomeric units were generated using PolyParGen. Initially, 90 PVDF and 30 PDA chains were packed in a box of dimension 5.2 nm \u003cb\u003e\u0026times;\u003c/b\u003e 5.2 nm \u003cb\u003e\u0026times;\u003c/b\u003e 5 nm, and the system (membrane) was equilibrated in the \u003cem\u003eNP\u003c/em\u003e\u003csub\u003e\u003cem\u003ez\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eT\u003c/em\u003e ensemble (with fixed pressure \u003cem\u003eP\u003c/em\u003e in the \u003cem\u003ez\u003c/em\u003e direction, allowing the box size to fluctuate perpendicular to the membrane) for 2.5 ns. The \u003cem\u003eNP\u003c/em\u003e\u003csub\u003e\u003cem\u003ez\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eT\u003c/em\u003e ensemble was applied to the system to allow the polymer membrane to match the piston area (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eL\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e), thus making the system periodic in the lateral directions. After equilibration of the membrane, the thickness of the membrane varied around 2.6\u0026ndash;3.5 nm resulting in a polymer density around 1.2\u0026ndash;1.39 g/cc. After the construction of the membrane, we inserted water molecules along with ions in the feed side and pure water on the permeate side, as per the numbers given in the previous subsection. Two graphene sheets were used as pistons at the respective free surface sides of feed and permeate reservoirs. Inside the polymer, we added GO sheets to create the nanocomposite membrane. The GO sheets consisted of graphene sheets with 66 carbon atoms with 34 OH groups and two COOH groups attached to the carbon atoms along the edge and on the basal plane of the graphene sheet, respectively. The C/O ratio thus obtained for the GO was around 1.79, which is higher than the experimental value (0.678), but it was required to ensure the stability of the functionalized GO sheets in the MD simulations. Moving forward, rGO-I sheets were prepared by attaching six C\u003csub\u003e6\u003c/sub\u003eNH\u003csub\u003e8\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e groups and three C\u003csub\u003e6\u003c/sub\u003eNH\u003csub\u003e8\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e groups at the edge of the GO sheets. Note that these groups are seen in the experiments after GO reacts with 2-isocynatoethyl methacrylate. A similar methodology was followed after adding a different concentration of rGO-I sheets with 90 PVDF and 30 PDA chains to prepare an rGO-I@IPN_LC membrane. We also observed that, after equilibration of the rGO-I@IPN membrane in the \u003cem\u003eNP\u003c/em\u003e\u003csub\u003e\u003cem\u003ez\u003c/em\u003e\u003c/sub\u003e\u003cem\u003eT\u003c/em\u003e ensemble, the interlayer distance was found to be around 0.60 nm, which is similar to what was observed in the experiments (0.62 nm).\u003c/p\u003e"},{"header":"DECLARATIONS","content":"\u003cp\u003e\u003cstrong\u003eSUPPLEMENTARY INFORMATION\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformation about the characterization techniques, polarized optical microscopy (POM) images of\u0026nbsp;rGO-I@IPN_LC dope solutions,\u0026nbsp;N\u003csub\u003e2\u0026nbsp;\u003c/sub\u003eadsorption/desorption isotherm of rGO-I@IPN_LC membrane, plots of pore size distributions employing the NLDFT method is shown in the inset, XRD pattern of dry rGO-I@IPN_LC and wet rGO-I@IPN_LC membranes, \u0026nbsp;UV plot of water after 5 days and 90 days water exposure of GO and rGO-I@IPN_LC membrane respectively, representatives of the 2D X-ray scattering patterns of the rGO-I@IPN_LC membrane, deconvolution XPS value of C, N,O, and F, and temporal water permeation behaviour from MD simulations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eR.S.G., S.S.I., and D.P. contributed equally. R.S.G. and S.S.I. conceived the project idea, and performed the experiments. R.S.G and S.S.I. wrote the paper. D.P. carried out the MD simulations and analyzed the resulting data. A.G.R. supervised the MD simulation work. D.P. and A.G.R. wrote the simulations part of the paper. S.B. supervised the project and intellectual inputs came from S.B. and S.S.I.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDisclosure statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eACKNOWLEDGMENTS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eR.S.G would like to acknowledge the Ministry of Education for the Prime Minister\u0026rsquo;s Research Fellowship (PMRF). S.S.I. thanks the Science and Engineering Research Board (SERB) for the National Post Doctoral Fellowship (File No.: PDF/2021/000629). S.B. acknowledges the SERB Swarnajayanti Fellowship for carrying out the research. R.S.G and S.S.I. acknowledge the Department of Materials Engineering and CeNSE, Indian Institute of Science, for the opportunity to carry out research. A.G.R. acknowledges financial support from the SERB via a Core Research Grant (CRG) (File No.: CRG/2021/002792) and the Infosys Foundation, Bengaluru for an Infosys Young Investigator grant. D.P. acknowledges Bharath Desikan for his assistance with the Gromacs software. The authors acknowledge the computational facilities provided by the Supercomputer Education and Research Centre at the Indian Institute of Science for computing facilities.\u003c/p\u003e"},{"header":"REFERENCES","content":"\u003col\u003e\n\u003cli\u003ePathan, S.\u003cem\u003e et al.\u003c/em\u003e Fundamental Understanding of Ultrathin, Highly Stable Self-Assembled Liquid Crystalline Graphene Oxide Membranes Leading to Precise Molecular Sieving through Non-equilibrium Molecular Dynamics. \u003cem\u003eACS nano\u003c/em\u003e (2023).\u003c/li\u003e\n\u003cli\u003eSamantaray, P. K., Sen Gupta, R. \u0026amp; Bose, S. Self‐Assembly in \u0026ldquo;Matrix‐Free\u0026rdquo; Functionalized Boron Nitride Sheets as Free‐Standing Thin Film Sieves for Stable Forward Osmosis and Robust Dye Removal Applications. \u003cem\u003eAdvanced Sustainable Systems\u003c/em\u003e, 2200385.\u003c/li\u003e\n\u003cli\u003eSen Gupta, R., Padmavathy, N. \u0026amp; Bose, S. The Journey of Water Remediation through Biomimetic Strategies: A Mechanistic Insight. \u003cem\u003eAdvanced Sustainable Systems\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 2100213 (2021).\u003c/li\u003e\n\u003cli\u003eVan der Bruggen, B. Sustainable implementation of innovative technologies for water purification. \u003cem\u003eNature Reviews Chemistry\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 217-218 (2021).\u003c/li\u003e\n\u003cli\u003eFaucher, S.\u003cem\u003e et al.\u003c/em\u003e Critical knowledge gaps in mass transport through single-digit nanopores: A review and perspective. \u003cem\u003eThe Journal of Physical Chemistry C\u003c/em\u003e \u003cstrong\u003e123\u003c/strong\u003e, 21309-21326 (2019).\u003c/li\u003e\n\u003cli\u003eSharma, B. B. \u0026amp; Govind Rajan, A. How grain boundaries and interfacial electrostatic interactions modulate water desalination via nanoporous hexagonal boron nitride. \u003cem\u003eThe Journal of Physical Chemistry B\u003c/em\u003e \u003cstrong\u003e126\u003c/strong\u003e, 1284-1300 (2022).\u003c/li\u003e\n\u003cli\u003eTiwary, S. K., Singh, M., Chavan, S. V. \u0026amp; Karim, A. Graphene oxide-based membranes for water desalination and purification. \u003cem\u003enpj 2D Materials and Applications\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e, 27 (2024).\u003c/li\u003e\n\u003cli\u003ePadmavathy, N., Behera, S. S., Pathan, S., Das Ghosh, L. \u0026amp; Bose, S. Interlocked graphene oxide provides narrow channels for effective water desalination through forward osmosis. \u003cem\u003eACS applied materials \u0026amp; interfaces\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 7566-7575 (2019).\u003c/li\u003e\n\u003cli\u003eHuang, H.\u003cem\u003e et al.\u003c/em\u003e Ultrafast viscous water flow through nanostrand-channelled graphene oxide membranes. \u003cem\u003eNature communications\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, 2979 (2013).\u003c/li\u003e\n\u003cli\u003eSun, P.\u003cem\u003e et al.\u003c/em\u003e Selective ion penetration of graphene oxide membranes. \u003cem\u003eACS nano\u003c/em\u003e \u003cstrong\u003e7\u003c/strong\u003e, 428-437 (2013).\u003c/li\u003e\n\u003cli\u003eThebo, K. H.\u003cem\u003e et al.\u003c/em\u003e Highly stable graphene-oxide-based membranes with superior permeability. \u003cem\u003eNature communications\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 1486 (2018).\u003c/li\u003e\n\u003cli\u003eLi, W., Wu, W. \u0026amp; Li, Z. Controlling interlayer spacing of graphene oxide membranes by external pressure regulation. \u003cem\u003eAcs Nano\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 9309-9317 (2018).\u003c/li\u003e\n\u003cli\u003eJamil, N.\u003cem\u003e et al.\u003c/em\u003e Mixed matrix membranes incorporated with reduced graphene oxide (rGO) and zeolitic imidazole framework-8 (ZIF-8) nanofillers for gas separation. \u003cem\u003eJournal of Solid State Chemistry\u003c/em\u003e \u003cstrong\u003e270\u003c/strong\u003e, 419-427 (2019).\u003c/li\u003e\n\u003cli\u003eAlayande, A. B., Park, H. D., Vrouwenvelder, J. S. \u0026amp; Kim, I. S. Implications of chemical reduction using hydriodic acid on the antimicrobial properties of graphene oxide and reduced graphene oxide membranes. \u003cem\u003eSmall\u003c/em\u003e \u003cstrong\u003e15\u003c/strong\u003e, 1901023 (2019).\u003c/li\u003e\n\u003cli\u003eMohammed, S. A.\u003cem\u003e et al.\u003c/em\u003e CO2/N2 selectivity enhancement of PEBAX MH 1657/Aminated partially reduced graphene oxide mixed matrix composite membrane. \u003cem\u003eSeparation and Purification Technology\u003c/em\u003e \u003cstrong\u003e223\u003c/strong\u003e, 142-153 (2019).\u003c/li\u003e\n\u003cli\u003eLiu, Z., Xu, Z., Hu, X. \u0026amp; Gao, C. Lyotropic liquid crystal of polyacrylonitrile-grafted graphene oxide and its assembled continuous strong nacre-mimetic fibers. \u003cem\u003eMacromolecules\u003c/em\u003e \u003cstrong\u003e46\u003c/strong\u003e, 6931-6941 (2013).\u003c/li\u003e\n\u003cli\u003eXu, Z. \u0026amp; Gao, C. Aqueous liquid crystals of graphene oxide. \u003cem\u003eACS nano\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 2908-2915 (2011).\u003c/li\u003e\n\u003cli\u003eZhang, Y.\u003cem\u003e et al.\u003c/em\u003e Rapid fabrication by lyotropic self-assembly of thin nanofiltration membranes with uniform 1 nanometer pores. \u003cem\u003eACS nano\u003c/em\u003e \u003cstrong\u003e15\u003c/strong\u003e, 8192-8203 (2021).\u003c/li\u003e\n\u003cli\u003eYun, T., Jeong, G. H., Padmajan Sasikala, S. \u0026amp; Kim, S. O. 2D graphene oxide liquid crystal for real-world applications: Energy, environment, and antimicrobial. \u003cem\u003eAPL Materials\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e, 070903 (2020).\u003c/li\u003e\n\u003cli\u003eHegde, M.\u003cem\u003e et al.\u003c/em\u003e Strong graphene oxide nanocomposites from aqueous hybrid liquid crystals. \u003cem\u003eNature Communications\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 830 (2020).\u003c/li\u003e\n\u003cli\u003eJalili, R.\u003cem\u003e et al.\u003c/em\u003e Formation and processability of liquid crystalline dispersions of graphene oxide. \u003cem\u003eMaterials Horizons\u003c/em\u003e \u003cstrong\u003e1\u003c/strong\u003e, 87-91 (2014).\u003c/li\u003e\n\u003cli\u003eMahalingam, D. K., Wang, S. \u0026amp; Nunes, S. P. Graphene oxide liquid crystal membranes in protic ionic liquid for nanofiltration. \u003cem\u003eACS Applied Nano Materials\u003c/em\u003e \u003cstrong\u003e1\u003c/strong\u003e, 4661-4670 (2018).\u003c/li\u003e\n\u003cli\u003eAkbari, A.\u003cem\u003e et al.\u003c/em\u003e Large-area graphene-based nanofiltration membranes by shear alignment of discotic nematic liquid crystals of graphene oxide. \u003cem\u003eNature communications\u003c/em\u003e \u003cstrong\u003e7\u003c/strong\u003e, 10891 (2016).\u003c/li\u003e\n\u003cli\u003eGuo, F.\u003cem\u003e et al.\u003c/em\u003e Hydration-responsive folding and unfolding in graphene oxide liquid crystal phases. \u003cem\u003eAcs Nano\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 8019-8025 (2011).\u003c/li\u003e\n\u003cli\u003eMa, F.-f.\u003cem\u003e et al.\u003c/em\u003e Blend-electrospun poly (vinylidene fluoride)/polydopamine membranes: self-polymerization of dopamine and the excellent adsorption/separation abilities. \u003cem\u003eJournal of Materials Chemistry A\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 14430-14443 (2017).\u003c/li\u003e\n\u003cli\u003eShao, L., Wang, Z. X., Zhang, Y. L., Jiang, Z. X. \u0026amp; Liu, Y. Y. A facile strategy to enhance PVDF ultrafiltration membrane performance via self-polymerized polydopamine followed by hydrolysis of ammonium fluotitanate. \u003cem\u003eJournal of Membrane Science\u003c/em\u003e \u003cstrong\u003e461\u003c/strong\u003e, 10-21 (2014).\u003c/li\u003e\n\u003cli\u003eXu, L. Q., Yang, W. J., Neoh, K.-G., Kang, E.-T. \u0026amp; Fu, G. D. Dopamine-induced reduction and functionalization of graphene oxide nanosheets. \u003cem\u003eMacromolecules\u003c/em\u003e \u003cstrong\u003e43\u003c/strong\u003e, 8336-8339 (2010).\u003c/li\u003e\n\u003cli\u003eMohammadi Ghaleni, M.\u003cem\u003e et al.\u003c/em\u003e Fabrication of Janus membranes for desalination of oil-contaminated saline water. \u003cem\u003eACS applied materials \u0026amp; interfaces\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, 44871-44879 (2018).\u003c/li\u003e\n\u003cli\u003eSa, K.\u003cem\u003e et al.\u003c/em\u003e in \u003cem\u003eIOP Conference Series: Materials Science and Engineering.\u003c/em\u003e 012055 (IOP Publishing).\u003c/li\u003e\n\u003cli\u003eWu, T.\u003cem\u003e et al.\u003c/em\u003e Facile and low-cost approach towards a PVDF ultrafiltration membrane with enhanced hydrophilicity and antifouling performance via graphene oxide/water-bath coagulation. \u003cem\u003eRSC advances\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 7880-7889 (2015).\u003c/li\u003e\n\u003cli\u003eTene, T.\u003cem\u003e et al.\u003c/em\u003e Toward large-scale production of oxidized graphene. \u003cem\u003eNanomaterials\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, 279 (2020).\u003c/li\u003e\n\u003cli\u003eGupta, R. S., Padmavathy, N., Agarwal, P. \u0026amp; Bose, S. pH-triggered bio-inspired membranes engineered using sequential interpenetrating polymeric networks for tunable antibiotic and dye removal. \u003cem\u003eChemical Engineering Journal\u003c/em\u003e, 136997 (2022).\u003c/li\u003e\n\u003cli\u003eMuchtar, S., Wahab, M. Y., Mulyati, S., Arahman, N. \u0026amp; Riza, M. Superior fouling resistant PVDF membrane with enhanced filtration performance fabricated by combined blending and the self-polymerization approach of dopamine. \u003cem\u003eJournal of Water Process Engineering\u003c/em\u003e \u003cstrong\u003e28\u003c/strong\u003e, 293-299 (2019).\u003c/li\u003e\n\u003cli\u003eChung, T. S., Teoh, S. K. \u0026amp; Hu, X. Formation of ultrathin high-performance polyethersulfone hollow-fiber membranes. \u003cem\u003eJournal of membrane science\u003c/em\u003e \u003cstrong\u003e133\u003c/strong\u003e, 161-175 (1997).\u003c/li\u003e\n\u003cli\u003eWang, D.-M. \u0026amp; Lai, J.-Y. Recent advances in preparation and morphology control of polymeric membranes formed by nonsolvent induced phase separation. \u003cem\u003eCurrent Opinion in Chemical Engineering\u003c/em\u003e \u003cstrong\u003e2\u003c/strong\u003e, 229-237 (2013).\u003c/li\u003e\n\u003cli\u003eGuillen, G. R., Pan, Y., Li, M. \u0026amp; Hoek, E. M. Preparation and characterization of membranes formed by nonsolvent induced phase separation: a review. \u003cem\u003eIndustrial \u0026amp; Engineering Chemistry Research\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 3798-3817 (2011).\u003c/li\u003e\n\u003cli\u003eDutta, S., Gupta, R. S., Manna, K., Islam, S. S. \u0026amp; Bose, S. \u0026lsquo;Green-tea\u0026rsquo;extract soldered triple interpenetrating polymer network membranes for water remediation. \u003cem\u003eChemical Engineering Journal\u003c/em\u003e, 145008 (2023).\u003c/li\u003e\n\u003cli\u003eElbasuney, S., El-Sayyad, G. S., Tantawy, H. \u0026amp; Hashem, A. H. Promising antimicrobial and antibiofilm activities of reduced graphene oxide-metal oxide (RGO-NiO, RGO-AgO, and RGO-ZnO) nanocomposites. \u003cem\u003eRSC advances\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 25961-25975 (2021).\u003c/li\u003e\n\u003cli\u003eLi, B., Wang, S., Loh, X. J., Li, Z. \u0026amp; Chung, T.-S. Closed-loop recyclable membranes enabled by covalent adaptable networks for water purification. \u003cem\u003eProceedings of the National Academy of Sciences\u003c/em\u003e \u003cstrong\u003e120\u003c/strong\u003e, e2301009120 (2023).\u003c/li\u003e\n\u003cli\u003eLu, Y., Liu, W., Wang, K. \u0026amp; Zhang, S. Electropolymerized thin films with a microporous architecture enabling molecular sieving in harsh organic solvents under high temperature. \u003cem\u003eJournal of Materials Chemistry A\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, 20101-20110 (2022).\u003c/li\u003e\n\u003cli\u003eCseri, L.\u003cem\u003e et al.\u003c/em\u003e Bridging the interfacial gap in mixed-matrix membranes by nature-inspired design: Precise molecular sieving with polymer-grafted metal\u0026ndash;organic frameworks. \u003cem\u003eJournal of Materials Chemistry A\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 23793-23801 (2021).\u003c/li\u003e\n\u003cli\u003eCheng, Y.-T., Chu, K.-C., Tsao, H.-K. \u0026amp; Sheng, Y.-J. Size-dependent behavior and failure of young\u0026rsquo;s equation for wetting of two-component nanodroplets. \u003cem\u003eJournal of Colloid and Interface Science\u003c/em\u003e \u003cstrong\u003e578\u003c/strong\u003e, 69-76 (2020).\u003c/li\u003e\n\u003cli\u003eSeo, K. \u0026amp; Kim, M. in \u003cem\u003eSurface energy\u003c/em\u003e (InTechOpen, 2015).\u003c/li\u003e\n\u003cli\u003eElimelech, M., Chen, W. H. \u0026amp; Waypa, J. J. Measuring the zeta (electrokinetic) potential of reverse osmosis membranes by a streaming potential analyzer. \u003cem\u003eDesalination\u003c/em\u003e \u003cstrong\u003e95\u003c/strong\u003e, 269-286 (1994).\u003c/li\u003e\n\u003cli\u003eP\u0026eacute;rez-Mitta, G.\u003cem\u003e et al.\u003c/em\u003e Polydopamine meets solid-state nanopores: a bioinspired integrative surface chemistry approach to tailor the functional properties of nanofluidic diodes. \u003cem\u003eJournal of the American chemical Society\u003c/em\u003e \u003cstrong\u003e137\u003c/strong\u003e, 6011-6017 (2015).\u003c/li\u003e\n\u003cli\u003eMun, S. J.\u003cem\u003e et al.\u003c/em\u003e Tailored growth of graphene oxide liquid crystals with controlled polymer crystallization in GO-polymer composites. \u003cem\u003eNanoscale\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 2720-2727 (2021).\u003c/li\u003e\n\u003cli\u003eWong, G. C.\u003cem\u003e et al.\u003c/em\u003e Lamellar phase of stacked two-dimensional rafts of actin filaments. \u003cem\u003ePhysical review letters\u003c/em\u003e \u003cstrong\u003e91\u003c/strong\u003e, 018103 (2003).\u003c/li\u003e\n\u003cli\u003eKumar, P., Maiti, U. N., Lee, K. E. \u0026amp; Kim, S. O. Rheological properties of graphene oxide liquid crystal. \u003cem\u003eCarbon\u003c/em\u003e \u003cstrong\u003e80\u003c/strong\u003e, 453-461 (2014).\u003c/li\u003e\n\u003cli\u003eMezzenga, R.\u003cem\u003e et al.\u003c/em\u003e Shear rheology of lyotropic liquid crystals: a case study. \u003cem\u003eLangmuir\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 3322-3333 (2005).\u003c/li\u003e\n\u003cli\u003eDeng, J., You, Y., Bustamante, H., Sahajwalla, V. \u0026amp; Joshi, R. K. Mechanism of water transport in graphene oxide laminates. \u003cem\u003eChemical science\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e, 1701-1704 (2017).\u003c/li\u003e\n\u003cli\u003eGupta, R. S.\u003cem\u003e et al.\u003c/em\u003e Copper-substituted polyoxometalate-soldered interpenetrating polymeric networks membranes for water remediation. \u003cem\u003eChemical Engineering Journal\u003c/em\u003e \u003cstrong\u003e461\u003c/strong\u003e, 141949 (2023).\u003c/li\u003e\n\u003cli\u003eLi, R., Wu, Y., Shen, L., Chen, J. \u0026amp; Lin, H. A novel strategy to develop antifouling and antibacterial conductive Cu/polydopamine/polyvinylidene fluoride membranes for water treatment. \u003cem\u003eJournal of colloid and interface science\u003c/em\u003e \u003cstrong\u003e531\u003c/strong\u003e, 493-501 (2018).\u003c/li\u003e\n\u003cli\u003eSun, P.\u003cem\u003e et al.\u003c/em\u003e Selective trans-membrane transport of alkali and alkaline earth cations through graphene oxide membranes based on cation\u0026minus; \u0026pi; interactions. \u003cem\u003eAcs Nano\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e, 850-859 (2014).\u003c/li\u003e\n\u003cli\u003eHu, W.\u003cem\u003e et al.\u003c/em\u003e Graphene-based antibacterial paper. \u003cem\u003eACS nano\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, 4317-4323 (2010).\u003c/li\u003e\n\u003cli\u003eAkhavan, O. \u0026amp; Ghaderi, E. Toxicity of graphene and graphene oxide nanowalls against bacteria. \u003cem\u003eACS nano\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, 5731-5736 (2010).\u003c/li\u003e\n\u003cli\u003eAbadikhah, H., Naderi Kalali, E., Khodi, S., Xu, X. \u0026amp; Agathopoulos, S. Multifunctional thin-film nanofiltration membrane incorporated with reduced graphene oxide@ TiO2@ Ag nanocomposites for high desalination performance, dye retention, and antibacterial properties. \u003cem\u003eACS applied materials \u0026amp; interfaces\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 23535-23545 (2019).\u003c/li\u003e\n\u003cli\u003eSamantaray, P. K., Baloda, S., Madras, G. \u0026amp; Bose, S. A designer membrane tool-box with a mixed metal organic framework and RAFT-synthesized antibacterial polymer perform in tandem towards desalination, antifouling and heavy metal exclusion. \u003cem\u003eJournal of Materials Chemistry A\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, 16664-16679 (2018).\u003c/li\u003e\n\u003cli\u003eLiu, S.\u003cem\u003e et al.\u003c/em\u003e Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress. \u003cem\u003eACS nano\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 6971-6980 (2011).\u003c/li\u003e\n\u003cli\u003eBielawski, C., Dreyer, D., Park, S. \u0026amp; Ruoff, R. The chemistry of grapheme oxide. \u003cem\u003eChem. Soc. Rev\u003c/em\u003e \u003cstrong\u003e39\u003c/strong\u003e, 228-240 (2010).\u003c/li\u003e\n\u003cli\u003eGuo, F., Mukhopadhyay, A., Sheldon, B. W. \u0026amp; Hurt, R. H. Vertically aligned graphene layer arrays from chromonic liquid crystal precursors. \u003cem\u003eAdvanced materials\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, 508-513 (2011).\u003c/li\u003e\n\u003cli\u003eHurt, R. H. \u0026amp; Chen, Z.-Y. LIQUID CRYSTALS AND CARBON MATERIALS. \u003cem\u003ePhysics today\u003c/em\u003e \u003cstrong\u003e53\u003c/strong\u003e, 39-44 (2000).\u003c/li\u003e\n\u003cli\u003eDe Gennes, P.-G. \u0026amp; Prost, J. \u003cem\u003eThe physics of liquid crystals\u003c/em\u003e. (Oxford university press, 1993).\u003c/li\u003e\n\u003cli\u003eMukherjee, R., Bhunia, P. \u0026amp; De, S. Impact of graphene oxide on removal of heavy metals using mixed matrix membrane. \u003cem\u003eChemical Engineering Journal\u003c/em\u003e \u003cstrong\u003e292\u003c/strong\u003e, 284-297 (2016).\u003c/li\u003e\n\u003cli\u003eStankovich, S., Piner, R. D., Nguyen, S. T. \u0026amp; Ruoff, R. S. Synthesis and exfoliation of isocyanate-treated graphene oxide nanoplatelets. \u003cem\u003eCarbon\u003c/em\u003e \u003cstrong\u003e44\u003c/strong\u003e, 3342-3347 (2006).\u003c/li\u003e\n\u003cli\u003eZeron, I., Abascal, J. \u0026amp; Vega, C. A force field of Li+, Na+, K+, Mg2+, Ca2+, Cl\u0026minus;, and SO42\u0026minus; in aqueous solution based on the TIP4P/2005 water model and scaled charges for the ions. \u003cem\u003eThe Journal of chemical physics\u003c/em\u003e \u003cstrong\u003e151\u003c/strong\u003e (2019).\u003c/li\u003e\n\u003cli\u003eCheng, A. \u0026amp; Steele, W. Computer simulation of ammonia on graphite. I. Low temperature structure of monolayer and bilayer films. \u003cem\u003eThe Journal of chemical physics\u003c/em\u003e \u003cstrong\u003e92\u003c/strong\u003e, 3858-3866 (1990).\u003c/li\u003e\n\u003cli\u003eAbascal, J. L. \u0026amp; Vega, C. A general purpose model for the condensed phases of water: TIP4P/2005. \u003cem\u003eThe Journal of chemical physics\u003c/em\u003e \u003cstrong\u003e123\u003c/strong\u003e (2005).\u003c/li\u003e\n\u003cli\u003eJorgensen, W. L., Maxwell, D. S. \u0026amp; Tirado-Rives, J. Development and testing of the OPLS all-atom force field on conformational energetics and properties of organic liquids. \u003cem\u003eJournal of the American Chemical Society\u003c/em\u003e \u003cstrong\u003e118\u003c/strong\u003e, 11225-11236 (1996).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":false,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Liquid crystals, sequential IPN, mixed matrix membranes, antifouling, antibacterial, non-cytotoxic, salt rejection, nanofiltration, dye removal, antibiotic removal","lastPublishedDoi":"10.21203/rs.3.rs-4381911/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4381911/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eGraphene oxide (GO)-based membranes hold great promise for revolutionizing nanofiltration, thanks to their seamless water transport and efficient ion and molecular sieving capabilities. However, challenges such as membrane disintegration under high pressure and nanochannel swelling due to water intercalation hinder their upscaling. In this study, we addressed these issues by aligning GO-based liquid crystals through shear forces and stabilizing their stacking using a sequential interpenetrating polymeric network (IPN) via electrostatic anchorage. This approach retained long-range order through nanoconfinement. By carefully selecting starting materials for the IPN, such as dopamine and GO liquid crystals, we achieved a nematic phase at extremely low concentrations, a feat not achievable with conventional methods. The resulting membranes were extensively characterized using microscopic and spectroscopic techniques, revealing pore sizes in the range of 7 nm facilitated by nanomaterial inclusion. These highly ordered and structurally robust membranes exhibited exceptional water flux (145 LMH) and long-term separation efficiency (\u0026gt;\u0026thinsp;97%) for monovalent and divalent salts, dyes, and antibiotics. Molecular dynamics simulations provided detailed insights into the ionic sieving mechanism of the GO-based IPN membranes. The MD simulations support that the water flux is reduced upon arresting the rGO-I sheets within IPN which scales with the concentration of rGO-I. In addition, this confinement at molecular length scales leads to a reduction in the number of ions residing within the membrane region, favouring retention within the feed region. These results well corroborate with the observed experimental evidence. Moreover, the membranes showed antifouling, chlorine tolerance, antibacterial properties, and cytocompatibility. They remained stable over repeated operational periods and endured a wide range of harsh environmental conditions without swelling. These resilient and robust membranes pave the way for large-scale membrane fabrication and sustainable water treatment.\u003c/p\u003e","manuscriptTitle":"Sequential interpenetrating polymer network confines shear-aligned graphene oxide liquid crystals enabling precise molecular sieving","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-05-27 06:09:30","doi":"10.21203/rs.3.rs-4381911/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e173cde0-8ed4-4892-93bd-31343e6e0bc6","owner":[],"postedDate":"May 27th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":31754087,"name":"Scientific community and society/Water resources"},{"id":31754088,"name":"Physical sciences/Energy science and technology"}],"tags":[],"updatedAt":"2024-11-04T21:25:10+00:00","versionOfRecord":[],"versionCreatedAt":"2024-05-27 06:09:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4381911","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4381911","identity":"rs-4381911","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}