Fabrication of Low Cost Thermoresponsive Microgel@CuO Catalyst for Rapid Reduction of Methylene Blue Dye

Fabrication of Low Cost Thermoresponsive Microgel@CuO Catalyst for Rapid Reduction of Methylene Blue Dye | 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 Research Article Fabrication of Low Cost Thermoresponsive Microgel@CuO Catalyst for Rapid Reduction of Methylene Blue Dye Tarkeshwar Prasad, Poorn Prakash Pande, Krishna Kumar, Shailza Rai, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3858144/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Jun, 2024 Read the published version in Journal of Polymer Research → Version 1 posted 5 You are reading this latest preprint version Abstract The present study details the catalytic reduction of water pollutants (Methylene blue). In this research, the synthesis of microgels was achieved through free-radical emulsion polymerization techniques employing HEMA monomer as a crosslinker. Three different grades of microgel have synthesized by varying the amount of N-vinyl caprolactam. Copper-oxide nanoparticles were successfully incorporated into polymeric microgels through hydrothermal methods for catalytic reduction applications. Characterization of both microgels and microgel-nanoparticle composites was conducted using various techniques like as: Fourier transform infrared spectroscopy (FT-IR), powder X-Ray diffraction (Powder XRD) Dynamic light scattering (DLS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The catalytic reduction of methylene blue (MB) was characterized using ultraviolet-visible spectrometry. The catalytic reduction efficiency of the dye was measured by optimizing the parameter effect of crosslinking, temperature responsive monomer feed, temperature and amount of reducing agent (NaBH 4 ). Microgel nanocomposites respond to efficient catalysis at higher NVCL feed with moderate dose of NABH 4 . Core-Shell Microgel Catalysis Emulsion Polymerization Thermoresponive Polymer CuO nanoparticles Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 INTRODUCTION Water is a necessary part of human life and the environment. Due to the broad application of water in many areas, it is contaminated with unwanted substances [ 1 , 2 ]. Effluents from the textile industry, paper industry, pulp, and leather industry pollute the environment and float into the river [ 3 – 4 , 5 ]. Azo dye is one of the hazardous pollutants which are carcinogenic and mutagenic in nature [ 6 , 7 ]. Azo dyes have the N = N group that constitutes all coloring materials [ 8 ]. So, it is urgent to remove the toxic dyes. Several physical and chemical methods were used like adsorption [ 9 – 12 ], coagulation [ 13 ], flocculation [ 14 ], membrane separation [ 15 – 17 ], and chemical methods(reduction) [ 18 – 20 ]. In chemical reduction, the dye was converted into a useful compound. However, adsorption is a positive method in removing dyes from water bodies completely which needs highly efficient and effective adsorbents to do so. For chemical reduction, many reducing agents were used but they took a long time. Therefore, a catalytic reduction method opted for a new concept of composites microgel which acts as a catalyst [ 21 – 23 ]. Microgel is ultrahigh molecular mass, cross-linked polymer latex particle, three-dimensional, they differ substantially in structure, preparation, application, and physiochemical properties [ 24 – 26 ], and composites microgel is composed of metal nanoparticle (MNPs) with microgel. In catalytic property, MNPs coagulate as their surface energy is large and provides a less active center for adsorption to the reactant. To overcome this limitation microgel provide a nice network to stabilize the MNPs as microgel has many sieves NPs embedded into them and restricts coagulating. Many composites microgel has prepared by scientists. Bitar, et al. have studied the preparation of temperature and glucose-sensitive microgels synthesized via radical precipitation polymerization by using N-vinyl caprolactam (NVCL) as a monomer and N, N-methylene bis acrylamide as a crosslinker [ 27 ]. Ambreen et al. have reported the fabricated microgels with silver nanoparticles synthesized via free radical polymerization by using N-vinyl caprolactam (NVCL) and Acrylic Acid [ 28 ] and were used as a catalyst for the removal of water pollutants. Annegarn, et al. have reported the importance of pH in the synthesis of pH-responsive cationic microgel by using poly ( N -isopropyl acrylamide) (PNIPAM) and primary amine N -(3-aminopropyl) meth-acrylamide hydrochloride (APMH) [ 29 ]. Oberdisse, et al. was synthesized stimuli-responsive core-shell microgel particles and applied them to toxic pollutants [ 30 ]. Ozbas, et al. have reported the microgel based on acrylamide (AAM), 1-vinyl-2-pyrrolidone (NVP), and 2-(diethyl-amino) ethyl methacrylate (DEAEMA) by free radical precipitation polymerization which was used for the controlled drug release [ 31 ]. Town, A. R., et al. have reported the preparation of thermo-responsive poly (N-isopropyl acrylamide) based microgels [ 32 ]. Monodispersed microgels were prepared from poly (N-isopropyl acrylamide) and poly (N-isopropyl acrylamide-co-allylamine) via precipitation polymerization [ 33 ]. Zhifeng, et al. have reported the modulation of phase transition of N -isopropyl acrylamide (NIPAM) in the presence of poly (ethylene glycol) ether as a macro-comonomer and N, N-methylene bis acrylamide (MBA) as cross-linker based microgels for pulsatile drug release synthesized via surfactant free-radical polymerization [ 34 ]. Zhou, X. et al. have published their work on the ionic microgel loaded with gold nanoparticles, synthesized by using N-Isopropylacrylamide (NIPAM), 1-vinyl imidazole (VIM) as monomers, and 1,6-dibromohexane as cross-linker [ 35 ]. Luqman et al. have reported their work on the synthesis of sensitive hybrid polymer microgels in the presence of poly (N-isopropyl acrylamide-co-methacrylic acid-co-2-hydroxyethyl methacrylate) synthesized via free radical emulsion polymerization for catalytic reduction of organic pollutants [ 36 ]. Din, M. I. et al. have studied the synthesis of copper oxide nanoparticles in smart polymer microgel of poly (N-isopropyl meth acrylamide-co-methacrylic acid) via free radical precipitation method for catalytic reduction of methylene blue [ 37 ]. Atta, et al. have reported the hybrid ionic silver and magnetite microgels nanocomposites synthesized via using an in situ technique for efficient removal of methylene blue [ 38 ]. Ajmal, et al. work on the catalytic degradation of multiple organic compounds in the presence of poly (methacrylic acid-co-acrylonitrile)-Cu microgels composites synthesized via inverse suspension polymerization [ 39 ]. Kakar, M. U. have reported their work on the synthesis of carboxyl-functionalized PNIPAM microgels via soap-free emulsion polymerization for the catalytic activity [ 40 ]. Khan et al. have reported their first approach towards the in-situ synthesis of Fe nanoparticles in the presence of poly (N-isopropyl acrylamide-acrylic acid) microgel for catalytic reduction of organic pollutants [ 41 ]. In this current investigation, we focused on customizing a low-cost thermoresponsive microgel@CuO catalyst for the rapid reduction of a toxic organic dye, Methylene Blue. The thermoresponsive microgel with a core-shell structure was synthesized through free radical emulsion polymerization techniques. Styrene was utilized as the hydrophobic core, while Acrylamide, N-Vinyl caprolactam, and (Hydroxyethyl)methacrylate (HEMA) were employed as components for the thermoresponsive hydrophilic shell. Three distinct grades of microgel (G1 to G3) were synthesized by varying the proportions of NVCL. Subsequently, the microgel was adorned with Copper oxide (CuO) nanoparticles using a hydrothermal method to achieve a cost-effective catalyst. The catalytic performance of all grades was assessed for Methylene Blue reduction at low, medium, and high doses of the reducing agent (NaBH 4 ) and at temperatures of 25°C, 40°C, and 60°C. Notably, among the different grades, G3 exhibited excellent catalytic performance in the reduction of Methylene Blue, particularly at 60°C. Experimental section Materials and Methods N-Vinyl-Ꜫ-caprolactam (NVCL 98%, Tokyo Chemical Industry Co., Ltd.) was recrystallized by n-Hexane. Acrylamide (AM), Sodium Borohydride (NaBH 4 ), (Hydroxyethyl)methacrylate (HEMA) were procured from TCI, India and Sodium Dodecyl Sulfate (SDS) was purchased from Merck Life Science Pvt. Ltd. and were used as received. Styrene was purchased from Avra Synthesis Pvt. Ltd., India and it was purified by a 30% aqueous NaOH solution. Acetone and potassium persulphate (KPS) were bought from Spectrochem Pvt. Ltd., India and Copper Sulfate was obtained from Fisher Scientific, India. Double Distilled Water (DDW) and HPLC water were used during the work. Synthesis of Microgel (G) The microgel was formulated through the combination of Styrene (constituting the hydrophobic core), Acrylamide (forming the hydrophilic shell), N-vinyl-Ꜫ-caprolactam (contributing to the thermo-responsive shell), and (Hydroxyethyl)methacrylate (serving as the crosslinking agent). Various grades of microgels were synthesized using free radical emulsion solution polymerization techniques. In a 500 mL RB flask, 49.20 mM of Styrene and 39.3 mM of Acrylamide were combined, while the quantities of N-vinyl-Ꜫ-caprolactam and varied according to the grades (summarized in Table 1 ). The reaction mixture underwent a 30-minute nitrogen gas purge at room temperature, followed by the addition of 500 mg of SDS and the gradual pouring of 250 mL of Millipore water under N 2 purging. The RB flask was then placed in a preheated oil bath at 70 o C. Upon reaching 70 o C, 0.259 mM of KPS initiator was injected into the RB flask under nitrogen flow, resulting in a white suspension after 50–60 minutes. The reaction continued for 2 hours at the same temperature, followed by cooling the mixture to room temperature. Subsequent workup involved the use of acetone, filtration with a sintered funnel, and drying under a vacuum oven at 60 o C and 15 mm of Hg for 36 hours. Other grades were synthesized following the same procedure, with variations in the content of NVCL. The synthetic route of the microgel and detailed synthesis information are illustrated in Scheme 1 and Table 1 , respectively. Table 1 Synthetic details of synthesized grade of microgel. S. No. Microgel Styrene (mM) AM (mM) NVCL (mM) HEMA (mM) KPS (mM) SDS (mg) % Yield* 1. G1 49.20 39.3 3.6 9.72 0.259 500 91 2. G2 49.20 39.3 7.2 9.72 0.259 500 94 3. G3 49.20 39.3 10.8 9.72 0.259 500 97 *% Yield = (Wt. of Microgel/Wt. of Monomer + Wt. of Crosslinker) x 100 Synthesis of CuO Nanoparticles CuO nanoparticles were synthesized by the precipitation technique. Took 2 g of CuSO 4 .5H 2 O in a 250 mL RB flask and added 100 mL of HPLC water. This mixture was heated along with stirring and then, added 1 g of SDS at 60 o C and maintained the solution pH is 12, by the continuous pouring of 0.1 M NaOH solution dropwise. Afterwards, continued the reaction for 24 hrs. Subsequently, the precursor was collected and worked out with acetone then filtered & washed with C 2 H 5 OH: H 2 O (1:1) till pH changed from 14 to 7 and dried in vacuum oven at 60 o C for 24 hours in 15 mm of Hg. Then, the precursor calcined at 400 o C for 4 hours. The yield % of CuO nanoparticles is 91.6%. Synthesis of G/CuO nanoparticles composites Synthesis of G/CuO nanoparticles composites were performed by Hydrothermal Method. Took 250 mL of RB flask and charged by 1 g of Gs with 200 mg of CuO NPs in 20 mL of DD water. The RB flask was placed on the stirrer for 20 minutes with N 2 purging. Afterwards, sonicated the reaction mixture for 5 minutes and then the solution was transferred in an autoclave at the temperature 160 o C for 4 h. Cooled the composite and worked out with methanol then filtered the precipitate, and dried in an oven at 50 o C for 24 h in 15 mm of Hg. The synthetic route of G@CuO composite is shown in Scheme 2 . Characterizations Fourier Transform Infrared (FTIR) spectra of microgel and G@CuO composite were recorded on an ATR Thermo-Fisher Scientific-Nicolet iS5 instrument. Thermo-gravimetric analysis (TGA) of G and G@CuO composite was carried out on a TGA (TGA Q500, TA Instruments, USA) instrument operated in a temperature range from 35°C to 700°C with a scanning rate of 10°C min − 1 under nitrogen gas flow. Scanning Electron Microscope (SEM) imaging and EDX analysis of microgel and G@CuO composite were carried out on a Carl Zeiss model Ultra 55 microscope which was gold-coated before imaging in SEM. Transmission electron microscopy (TEM) studies of synthesized G and G@CuO composite were conducted on a JEOL (JEM Model No. F200) TEM machine at an accelerating voltage of 200 kV. The samples were prepared by placing a drop of ethanol dispersed polymers solution on carbon-coated copper (200 mesh) grids. Dynamic light scattering (DLS) Particle size measurements of ethanol dispersed samples (Microgel and G@CuO composite) were performed using a Zetasizer Nano S90 (Malvern Instruments, Germany) operating at a 4 mW He-Ne laser with 633 nm wavelength at 25 o C, 40 o C, and 60 o C. The powder x-ray diffraction patterns (XRD) of the microgel and G@CuO composite were collected in a Bruker D8 Advance powder diffraction apparatus. The membrane samples were placed on a glass slide, and the diffractograms were recorded with Cu Kα radiation (λ = 1.5406 Å) operated at 40 kV and 30 mA current in the angular range (2θ) of 5–60° at a scanning rate of 2°/minutes. UV-Vis spectrophotometer (Shimadzu UV- 2600) was performed for absorption spectra of Methylene Blue Dye removal. Among all synthesized grades, G3 and their composites were characterized. Applications Methylene blue dye removal by G@CuO composites In the study of Methylene Blue (MB) dye removal using G@CuO composites, various experimental steps were undertaken. The process involved taking 200 µL of MB solution (0.1 mg/mL) in a UV cuvette and introducing 10 mg of the composites. Different volumes from a stock solution of NaBH 4 (0.105 mM), specifically 100 µL, 200 µL, and 300 µL, were added to the mixture. The total volume in the UV cuvette was adjusted to 3 mL by incorporating distilled water. Subsequently, the removal of MB was examined and quantified through UV-Vis. spectroscopy and the absorption peak was used to estimation is 663 nm. The catalytic reduction performance of the synthesized grades, denoted as G1 to G3, was documented at temperatures of 25°C, 40°C, and 60°C. This comprehensive approach aimed to assess the efficiency of the G@CuO composites in catalyzing the reduction of Methylene Blue under varying conditions. Result and Discussion Synthesis of microgels and G@CuO composites Core-shell type microgel was synthesized by free-radical emulsion solution polymerization techniques. Microgel core was developed by polystyrene and shell through PAM, PNVCL, and PHEMA. The shell has crosslinked with the help of PHEMA, the substituents group having alcohol functionality and it have participating in hydrogen bonding with other polar groups like as: amide of PNVCL and PAM of parallel polymer chains as well as its covalently bonded with polymer backbone of vicinity chains [ 42 ]. The thermoresponsive properties of microgel have varied by feeding of PNVCL in three different grades (G1 to G3) of microgel. Different grades were synthesized by varying the amount of NVCL to moderate the materials thermo-responsive nature. The variation of grades has been done by the consideration of the ratio of hydrophobic and hydrophilic content of microgel with stability in aqueous medium. From G1 to G3 the hydrophilic feed increases, and it has favors monomer conversion with same initiator feeds of KPS, the results justified by % yield and G3 shows highest yield % i.e. 97%. The synthetic details are summarized in Table 1 . The feed of PNVCL corresponds to thermoresponsive nature of microgel swelling and deswelling properties. From G1 to G3, the PNVCL content increases with respect to increases the swelling properties of microgel matrix and at higher temperature the microgel shell (PNVCL) is least interact with aqueous medium and deswelling more in ascending grades. CuO nanoparticle was successfully synthesized by precipitation method using NaOH to completely convert into hydroxide precursor and then calcined the precursor into CuO nanoparticles forms. The main challenge is to stabilize the CuO nanoparticles in their native forms was achievable by immobilized in the thermoresponsive microgel matrix. The microgel hydrophilic shell of PAM, PNVCL and PHEMA polar groups are coordinated with CuO and stabilized into the matrix and deceased from the agglomeration and sedimentation process. All three grades of microgels were implemented for the synthesis of composites i.e, Microgel@CuO composites. The stability of nanoparticles in grades was interpreted by the catalytic performance of CuO nanoparticles by methylene blue dye reduction graphs. In all grades got the approximately same yield % i.e. ~ 96%. Characterization FTIR FTIR spectra of G3 and G3@CuO composite are depicted in Fig. 1 . In FTIR spectra of G3, the peak at 3430 cm − 1 appeared the of asymmetric -NH stretching of PAM and PNVCL. The peak at 1600 cm − 1 corresponds to combination of Amide I and II stretching of PAM and PNVCL, and -CO of PHEMA. The characteristics -CH stretching of polymer backbone was attributed at 2930 cm − 1 . Peaks appeared at 1450 cm − 1 and 1121 cm − 1 in microgel representing the combination of aromatic C = C (polystyrene) and –CH 2 vibrations, and -C-O stretching respectively. In FTIR spectra of G3@CuO composites, the stretching peak of amide 1 and amide II was shifted from 1600 to 1628 cm − 1 confirmed the bonding of CuO nanoparticles with polar amide group and it showed the CuO nanoparticle coordinated with the lone pair of nitrogen. The remaining peaks were the same as in microgel. The observed characteristic IR stretching and shifting confirmed the synthesis of microgel and composite. XRD XRD pattern of the copper nanoparticles is shown in Fig. 2 . In the XRD analysis of the microgel, there is only one hump was depicted 2θ value of 19.09⁰ and no crystalline peak was observed. Thus, microgel is amorphous structure and they were no unreacted monomer was present. In composites, the characteristics CuO nanoparticles planes (110), (002), (111), (200), and (220) were observed at 35.47°, 38.97°, 43.4 o , 50.4 o , and 74.2 o respectively. It indicates the CuO has monoclinic phase and JCPDS no. is 48-1548. The average crystallite size (t) has been calculated from the line broadening using Scherrer’s relation: t = 0.89λ /Bcosθ where λ is the wavelength of X-ray, B is the full width of half maximum (FWHM) and θ is the diffraction angle. The average crystallite size of CuO nanoparticles was calculated frompeak at θ = 50.4 o , is found to be 18.8 nm [ 43 ]. XRD graph of microgel and composites are shown in Fig. 2 . TGA Studies TGA pattern of G3 and G3@CuO composite is attribute in Fig. 3 . TGA analysis shows that G3 are thermally stable or working temperature below 370 o C. In the initial step the weight loss was observed at 100 o C due to loss of moisture content of gel and the % weight is 2.13%. The second weight loss was observed at 365 o C due to the loss of cross-linking of G3 shell and % weight is 8.32%. The glass transition temperature (T g ) of G3 is 410 o C and it was acheievd after the breaking of crosslinking in the matrix. Afterwards, at 441 o C, completely burnout the gel and only 2.5% residue was left. In G3@CuO composite, the moisture content was less than microgel i.e. 0.74%. In next step the crosslinking was vanished at 374 o C and the % weight loss is 7.47%. The T g value of composite is 427 o C. At 455 o C, the composite lost their polymer matrix and only the carbon rsidue and nanoparticles were left and the combine % weight is 24.53%. In all thermal weight loss stage the composite was found thermally more stable than microgel due to the CuO nanoparticles bound with the matrix polar group and provide rigidity which protect themselves from thermal vibrations. Hence, composite is thermally more stable than microgel matrix. Dynamic Light Scattering Analysis Figures 4 (A to C) and 4(D to F) show the hydrodynamic diameter of G3 and G3@CuO composite at 25 o C, 40 o C, and 60 o C. Dynamic light scattering exhibited a particle size distribution of G3 is 1919 nm, 1477 nm, and 833 nm at 25 o C, 40 o C, and 60 o C respectively. G3@CuO composite particle size exhibited a distribution of 1868 nm, 1070 nm and 716 nm at 25 o C, 40 o C, and 60 o C respectively. DLS analysis confirmed that in comparison to composite, microgel has more labile matrix in aqueous medium and it swells more. While increasing the temperature, both materials show excellent thermo-responsive and shrink their hydrodynamic diameter. These results confirmed that the bonded CuO nanoparticles decrease the number of available polar substituents to perform physiochemical interaction with the medium. Thus, the microgel and composite shows the excellent thermoresponsive behavior and the CuO nanoparticles successfully embedded in matrix in a stable form. Scanning Electron Microscopy (SEM) Studies The surface morphology of G3 and G3@CuO composite were obtained by SEM analysis shown in Fig. 5 (A) & 5(B) respectively. SEM image of microgel shows spherical shapes scattered morphology and particle size varying from 0.5 to 2 µm. In the composite SEM image, the spherical structures have the same particle size range, but the spherical structure is rougher, more textured and spindle shape was observed due to incorporation of CuO nanoparticles. The change of surface morphology confirmed that the Cu-NPs were successfully encapsulated in a microgel structure. Transmission Electron Microscopy (TEM) The shape and size of G3 and G3@CuO composite were obtained by TEM analysis shown in Fig. 6 (A) and 6(B). TEM image of microgel confirmed the formation of spherical shape and its size ranges between 100–200 nm. In the composite image, the microgel shape and size range is the same and the black dots represent the CuO-NPs 14 to 34 nm. TEM analysis confirmed the uniform distribution of NPs in microgel. EDAX Here, Fig. 7 shows the qualitative and quantitative EDAX analysis of microgel and nanocomposites. From the EDAX image of microgel, it was clear that only C and O peaks were observed and in nanocomposites, a Cu peak was also observed. Table 3 EDAX analysis of microgel and composite. S. No. Material Element Weight % Atomic % 1. Microgel CK NK OK 86.47 1.04 12.49 89.39 0.92 9.70 2. Microgel _Cu Composites CK NK OK Cu 58.23 0.33 21.32 20.12 74.35 0.36 20.44 4.86 In Table-3, the quantitative analysis of microgel was observed that C, N, and O have weight % is 6.47, 1.04, and 12.49%, and atomic % is 89.39, 0.92, and 9.70% respectively. In composite, weight % of C, N, O and Cu is 58.23, 0.33, 21.32 and 20.12% and atomic % is 74.35, 0.36, 20.44 and 4.86% respectively. EDAX analysis confirmed that Cu NPs successfully encapsulated in microgel structure. Applications Catalytic activity The catalytic activity of composites was recorded in respect of MB dye reduction by NaBH 4 as a reducing agent. The UV-Vis. spectra of all grades at room temperature (25 o C), 40 o C and 60 o C respective of different doses of NaBH 4 was recorded with Pseudo first order plots and depicted in Figs. 9 , 10 and 11 respectively. Negative of the slope of the graph plotted between lnA t /A o vs time gives the value of k app , and the corresponding values are given in Table 4 . The catalytic reduction of MB dye has been studied by all the grades with different doses of NaBH 4 varying the time at particular temperature. The nanocomposites have thermoresponsive behavior and it helps to control the catalytic reduction performance of CuO nanoparticles. The CuO nanoparticles have embedded on the thermoresponsive shell matrix which having the PNVCL chain, in above than moderate temperature 40 o C the caprolactam ring plays a thermal vibration and these could be restricted the interaction of shell with medium and the shell porous nature going to shrink. Thus, the CuO nanoparticles do not easily participate with the contaminated medium at higher temperature. Thus, this reduce the catalytic performance of nanoparticles at higher temperatures. In the kinetic studies of catalytic reduction of MB dye through the composites, the k app was determined by the pseudo first order reaction, in which the dye and composites content is fixed and varied the NaBH 4 doses. In which, the k app was highest at 200 µl (0.105 mM of NaBH 4 ) and the lower doses are not sufficient to the reduction or higher doses are not diffused to complete the reduction with higher rate. Temperature effect plays an important role in MB reduction by composites at room and moderate temperature the k app value is almost the same but at higher temperature its dramatically reduced to become inactive in catalytic reduction. Table 4 k app values in MB reductions in presence of the G1@CuO, G2@CuO and G3@CuO grades. Grade K app values (Sec. −1 ) Temperature 100 µL NaBH 4 200 µL NaBH 4 300 µL NaBH 4 G1@CuO 0.89 0.99 0.93 Room temperature (25 o C) G2@CuO 1.15 1.20 1.07 G3@CuO 1.40 1.87 1.33 G1@CuO 0.92 0.94 0.43 40 o C G2@CuO 1.09 1.22 0.66 G3@CuO 1.33 1.51 0.97 G1@CuO 0.24 0.18 0.13 60 o C G2@CuO 0.33 0.24 0.19 G3@CuO 0.43 0.34 0.26 It was observed that k app value increases from G1@CuO to G3@CuO in all the respective doses of NaBH 4 and temperature. From G1@CuO to G3@CuO the PNVCL content favors the catalytic performance with stability and is determined the k app values. Hence, The G3@CuO shows excellent catalytic performance in moderate dose of NaBH 4 at room temperature with the highest k app value of 1.87 Sec. −1 . Conclusion The thermoresponsive core-shell microgel was successfully synthesized by the free radical solution polymerization technique using polystyrene hydrophobic core and PAM, PNVCL and HEMA based hydrophilic shell. The developed microgel was established the crosslinking in shell by using the PHEMA content. The structure was confirmed by the FTIR techniques in which the characteristic stretching of all the content established the conclusion. The thermal studies confirm the materials are stable up to 360 o C and in comparison, to microgel composites are more stable. In the DLS analysis confirmed the deswelling and swelling properties of microgel and composites and it also depicts the negative thermoresponsive nature of microgel and composite. When the temperature rises the microgel and composite are de-swell. The electronic micrographs also confirmed the change in surface morphology between microgel and composites and attributed the size and shape of microgel and composites. The XRD analysis shows the amorphous nature of microgel and semicrystalline nature of composites. It confirmed the monoclinic phase of CuO nanoparticles and found the size range of nanoparticles in composite is ~ 18.8 nm. The catalytic reduction of MB dye was estimated by using different parameters like temperature and NaBH 4 doses and the kinetic studies followed the pseudo first order reaction. The k app value confirmed the catalytic performance of composite was performed well at moderate NaBH 4 dose at 40 o C. The composite shows inactivity at higher temperatures in catalytic reduction of MB dye due to their thermoresponsive nature. So, the synthesized catalyst worked in low concentrations of NaBH 4 at normal temperature and checked the catalytic reaction at higher temperatures. The key role of catalyst to switch the catalytic reaction by varying the temperature of medium. This is the potential candidate to use in the treatment of industrial wastewater at low cost. Declarations Acknowledgement This work was financially supported by the Science Engineering and Research Board (TAR/2020/000351), New Delhi, Government of India. Declaration of interest Statement We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. 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Simultaneous catalytic degradation/reduction of multiple organic compounds by modifiable p(meth acrylic acid-co-acrylonitrile)–M (M: Cu, Co) microgel catalyst composites. New Journal of Chemistry 40(2): 1485–1496 . Kakar MU, Khan K, Akram M, Sami R, Khojah E, Iqbal I, Dai R (2021) Synthesis of bimetallic nanoparticles loaded on to PNIPAM hybrid microgel and their catalytic activity. Scientific Reports 11(1). Khan S R, Ali S, Ullah B, Jamil S, Zanib T (2020) Synthesis of iron nanoparticles in poly (N-isopropylacrylamide-acrylic acid) hybrid microgels for catalytic reduction of series of organic pollutants: a first approach. J of Nanoparticle Res 22(7). Singh VK, Kumar K, Singh N, Tiwari R, Krishnamoorthi S (2022) Swift catalytic reduction of hazardous pollutants by new generation microgels. Soft Matter18(3): 535-544. 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Cite Share Download PDF Status: Published Journal Publication published 01 Jun, 2024 Read the published version in Journal of Polymer Research → Version 1 posted Reviewers agreed at journal 13 Feb, 2024 Reviewers invited by journal 05 Feb, 2024 Editor invited by journal 17 Jan, 2024 Editor assigned by journal 15 Jan, 2024 First submitted to journal 12 Jan, 2024 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-3858144","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":271452728,"identity":"009eacff-1127-4791-80d2-d0348ade2b5d","order_by":0,"name":"Tarkeshwar Prasad","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Tarkeshwar","middleName":"","lastName":"Prasad","suffix":""},{"id":271452729,"identity":"13eeecc3-5b98-4dc7-9717-cac295abf9c3","order_by":1,"name":"Poorn Prakash 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20:42:34","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3858144/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3858144/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10965-024-04022-3","type":"published","date":"2024-06-01T15:28:07+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":50935953,"identity":"55e9d10b-bd34-46bd-b384-7c11e5d98e09","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":153673,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR Spectra of G3 and G3@CuO composite.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/a58d26f759cb02619ce07f70.png"},{"id":50935954,"identity":"e45be08b-4ef5-4f77-a313-b610bd12f9da","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":94891,"visible":true,"origin":"","legend":"\u003cp\u003eXRD graph of microgel and composites.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/f7c24cde7c1c994cc4bb9ee8.png"},{"id":50935951,"identity":"4de91120-2b0f-4a05-9356-9eae648df62d","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":74609,"visible":true,"origin":"","legend":"\u003cp\u003eTGA curve of microgel and composites.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/827a2afacc86ba371a9453d2.png"},{"id":50936108,"identity":"b6516f92-1a38-4758-b8b7-ff5fe98ff58e","added_by":"auto","created_at":"2024-02-09 20:49:35","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":48117,"visible":true,"origin":"","legend":"\u003cp\u003eParticle size analysis of microgel at (A) 25 \u003csup\u003eo\u003c/sup\u003eC, (B) 40 \u003csup\u003eo\u003c/sup\u003eC and (C) 60 \u003csup\u003eo\u003c/sup\u003eC and composites at (D) 25 \u003csup\u003eo\u003c/sup\u003eC, (E) 40 \u003csup\u003eo\u003c/sup\u003eC and (F) 60 \u003csup\u003eo\u003c/sup\u003eC.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/a19c257b6ce181bdb654c1be.png"},{"id":50935956,"identity":"5e665d61-6e5e-4c7f-942a-fbe04510e366","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":690795,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of microgel and composites\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/ba0efd88ae8496ebd6a45c10.png"},{"id":50935958,"identity":"ec435d45-2a53-4431-8725-9717147910d4","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1050709,"visible":true,"origin":"","legend":"\u003cp\u003eTEM image of microgel (A) and composite (B)\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/dad5cb3a592e93109441c6ee.png"},{"id":50935963,"identity":"d9e43c8e-e39b-4705-bc4b-98653968e7a9","added_by":"auto","created_at":"2024-02-09 20:41:35","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":652471,"visible":true,"origin":"","legend":"\u003cp\u003e(A) SEM image of G3, (B) quantitative analysis of elements presents in G3, (C) elemental spectra of G3 and (D) element distribution on G3 surface (Red, green and blue dot represents C, N and O respectively).\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/56ddda7735b82adf41c8430a.png"},{"id":50935959,"identity":"f26797fc-5ec1-44ac-b696-3fe8125e90aa","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":602855,"visible":true,"origin":"","legend":"\u003cp\u003e(A) SEM image of G3@CuO, (B) quantitative analysis of elements presents in G3@CuO, (C) elemental spectra of G3@CuO and (D) element distribution on G3@CuO surface (Yellow, red, green and blue dot represents Cu, C, N and O respectively).\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/2a4bfd5ec6b9fabbde6c6e5e.png"},{"id":50935955,"identity":"363af890-3575-4bcc-9aa8-e0ba39d7810c","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":1213250,"visible":true,"origin":"","legend":"\u003cp\u003eTime dependent UV-Vis. absorption spectra of MB dye in its reduction by using (A) G1@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT (B) G2@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT and (C) G3@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT, (D) G1@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT, (E) G2@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT, (F) G3@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT, (G) G1@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT, (H) G2@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT, (I) G3@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at RT, (J) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G1@CuO, (K) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G2@CuO and (L) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G3@CuO\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/0ab39780971255bc37d8d46d.png"},{"id":50935960,"identity":"54475dbe-46e6-4160-9b6e-2d0071d491c4","added_by":"auto","created_at":"2024-02-09 20:41:35","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1386375,"visible":true,"origin":"","legend":"\u003cp\u003eTime dependent UV-Vis. absorption spectra of MB dye in its reduction by using (A) G1@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC (B) G2@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC and (C) G3@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC, (D) G1@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC, (E) G2@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC, (F) G3@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC, (G) G1@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC, (H) G2@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC, (I) G3@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 40\u003csup\u003eo\u003c/sup\u003eC, (J) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G1@CuO, (K) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G2@CuO and (L) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G3@CuO.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/c032884efcef6a021a4eca3c.png"},{"id":50935961,"identity":"c27767b4-cb90-4b8f-8577-bede43986bbc","added_by":"auto","created_at":"2024-02-09 20:41:35","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":1332740,"visible":true,"origin":"","legend":"\u003cp\u003eTime dependent UV-Vis. absorption spectra of MB dye in its reduction by using (A) G1@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC (B) G2@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC and (C) G3@CuO, 100µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC, (D) G1@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC, (E) G2@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC, (F) G3@CuO, 200µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC, (G) G1@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC, (H) G2@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC, (I) G3@CuO, 300µl of NaBH\u003csub\u003e4\u003c/sub\u003e at 60\u003csup\u003eo\u003c/sup\u003eC, (J) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G1@CuO, (K) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G2@CuO and (L) Pseudo first order plot of lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time of MB dye using G3@CuO.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/dd96406f3745caa1c430f115.png"},{"id":58823298,"identity":"dbef3159-2f37-4d3f-b84a-3ff9b3cf035f","added_by":"auto","created_at":"2024-06-21 16:57:33","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":7478650,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/59a630fd-8d05-4119-b7bd-778f8357fb02.pdf"},{"id":50935950,"identity":"85440362-1365-425d-a367-8f0f7c30a1ee","added_by":"auto","created_at":"2024-02-09 20:41:34","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":98643,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1 \u003c/strong\u003eSynthetic route of microgel.\u003c/p\u003e","description":"","filename":"scheme1.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/2cc5c9eff0bdbaefa3009506.png"},{"id":50936107,"identity":"e39d246b-81e1-4b25-ad98-266ecc534540","added_by":"auto","created_at":"2024-02-09 20:49:34","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":107974,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 2 \u003c/strong\u003eSynthetic route of G@CuO nanoparticle composites.\u003c/p\u003e","description":"","filename":"scheme2.png","url":"https://assets-eu.researchsquare.com/files/rs-3858144/v1/27942e5da8aa11460e6962ce.png"}],"financialInterests":"","formattedTitle":"Fabrication of Low Cost Thermoresponsive Microgel@CuO Catalyst for Rapid Reduction of Methylene Blue Dye","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eWater is a necessary part of human life and the environment. Due to the broad application of water in many areas, it is contaminated with unwanted substances [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Effluents from the textile industry, paper industry, pulp, and leather industry pollute the environment and float into the river [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Azo dye is one of the hazardous pollutants which are carcinogenic and mutagenic in nature [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Azo dyes have the N\u0026thinsp;=\u0026thinsp;N group that constitutes all coloring materials [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. So, it is urgent to remove the toxic dyes. Several physical and chemical methods were used like adsorption [\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], coagulation [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], flocculation [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], membrane separation [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and chemical methods(reduction) [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In chemical reduction, the dye was converted into a useful compound. However, adsorption is a positive method in removing dyes from water bodies completely which needs highly efficient and effective adsorbents to do so. For chemical reduction, many reducing agents were used but they took a long time. Therefore, a catalytic reduction method opted for a new concept of composites microgel which acts as a catalyst [\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Microgel is ultrahigh molecular mass, cross-linked polymer latex particle, three-dimensional, they differ substantially in structure, preparation, application, and physiochemical properties [\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], and composites microgel is composed of metal nanoparticle (MNPs) with microgel. In catalytic property, MNPs coagulate as their surface energy is large and provides a less active center for adsorption to the reactant. To overcome this limitation microgel provide a nice network to stabilize the MNPs as microgel has many sieves NPs embedded into them and restricts coagulating. Many composites microgel has prepared by scientists.\u003c/p\u003e \u003cp\u003eBitar, et al. have studied the preparation of temperature and glucose-sensitive microgels synthesized via radical precipitation polymerization by using N-vinyl caprolactam (NVCL) as a monomer and N, N-methylene bis acrylamide as a crosslinker [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Ambreen et al. have reported the fabricated microgels with silver nanoparticles synthesized via free radical polymerization by using N-vinyl caprolactam (NVCL) and Acrylic Acid [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] and were used as a catalyst for the removal of water pollutants. Annegarn, et al. have reported the importance of pH in the synthesis of pH-responsive cationic microgel by using poly (\u003cem\u003eN\u003c/em\u003e-isopropyl acrylamide) (PNIPAM) and primary amine \u003cem\u003eN\u003c/em\u003e-(3-aminopropyl) meth-acrylamide hydrochloride (APMH) [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Oberdisse, et al. was synthesized stimuli-responsive core-shell microgel particles and applied them to toxic pollutants [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Ozbas, et al. have reported the microgel based on acrylamide (AAM), 1-vinyl-2-pyrrolidone (NVP), and 2-(diethyl-amino) ethyl methacrylate (DEAEMA) by free radical precipitation polymerization which was used for the controlled drug release [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Town, A. R., et al. have reported the preparation of thermo-responsive poly (N-isopropyl acrylamide) based microgels [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Monodispersed microgels were prepared from poly (N-isopropyl acrylamide) and poly (N-isopropyl acrylamide-co-allylamine) via precipitation polymerization [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Zhifeng, et al. have reported the modulation of phase transition of \u003cem\u003eN\u003c/em\u003e-isopropyl acrylamide (NIPAM) in the presence of poly (ethylene glycol) ether as a macro-comonomer and N, N-methylene bis acrylamide (MBA) as cross-linker based microgels for pulsatile drug release synthesized via surfactant free-radical polymerization [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Zhou, X. et al. have published their work on the ionic microgel loaded with gold nanoparticles, synthesized by using N-Isopropylacrylamide (NIPAM), 1-vinyl imidazole (VIM) as monomers, and 1,6-dibromohexane as cross-linker [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Luqman et al. have reported their work on the synthesis of sensitive hybrid polymer microgels in the presence of poly (N-isopropyl acrylamide-co-methacrylic acid-co-2-hydroxyethyl methacrylate) synthesized via free radical emulsion polymerization for catalytic reduction of organic pollutants [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Din, M. I. et al. have studied the synthesis of copper oxide nanoparticles in smart polymer microgel of poly (N-isopropyl meth acrylamide-co-methacrylic acid) via free radical precipitation method for catalytic reduction of methylene blue [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Atta, et al. have reported the hybrid ionic silver and magnetite microgels nanocomposites synthesized via using an in situ technique for efficient removal of methylene blue [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Ajmal, et al. work on the catalytic degradation of multiple organic compounds in the presence of poly (methacrylic acid-co-acrylonitrile)-Cu microgels composites synthesized via inverse suspension polymerization [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Kakar, M. U. have reported their work on the synthesis of carboxyl-functionalized PNIPAM microgels via soap-free emulsion polymerization for the catalytic activity [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Khan et al. have reported their first approach towards the in-situ synthesis of Fe nanoparticles in the presence of poly (N-isopropyl acrylamide-acrylic acid) microgel for catalytic reduction of organic pollutants [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this current investigation, we focused on customizing a low-cost thermoresponsive microgel@CuO catalyst for the rapid reduction of a toxic organic dye, Methylene Blue. The thermoresponsive microgel with a core-shell structure was synthesized through free radical emulsion polymerization techniques. Styrene was utilized as the hydrophobic core, while Acrylamide, N-Vinyl caprolactam, and (Hydroxyethyl)methacrylate (HEMA) were employed as components for the thermoresponsive hydrophilic shell. Three distinct grades of microgel (G1 to G3) were synthesized by varying the proportions of NVCL.\u003c/p\u003e \u003cp\u003eSubsequently, the microgel was adorned with Copper oxide (CuO) nanoparticles using a hydrothermal method to achieve a cost-effective catalyst. The catalytic performance of all grades was assessed for Methylene Blue reduction at low, medium, and high doses of the reducing agent (NaBH\u003csub\u003e4\u003c/sub\u003e) and at temperatures of 25\u0026deg;C, 40\u0026deg;C, and 60\u0026deg;C. Notably, among the different grades, G3 exhibited excellent catalytic performance in the reduction of Methylene Blue, particularly at 60\u0026deg;C.\u003c/p\u003e"},{"header":"Experimental section","content":"\n\u003ch3\u003eMaterials and Methods\u003c/h3\u003e\n\u003cp\u003eN-Vinyl-Ꜫ-caprolactam (NVCL 98%, Tokyo Chemical Industry Co., Ltd.) was recrystallized by n-Hexane. Acrylamide (AM), Sodium Borohydride (NaBH\u003csub\u003e4\u003c/sub\u003e), (Hydroxyethyl)methacrylate (HEMA) were procured from TCI, India and Sodium Dodecyl Sulfate (SDS) was purchased from Merck Life Science Pvt. Ltd. and were used as received. Styrene was purchased from Avra Synthesis Pvt. Ltd., India and it was purified by a 30% aqueous NaOH solution. Acetone and potassium persulphate (KPS) were bought from Spectrochem Pvt. Ltd., India and Copper Sulfate was obtained from Fisher Scientific, India. Double Distilled Water (DDW) and HPLC water were used during the work.\u003c/p\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of Microgel (G)\u003c/h2\u003e \u003cp\u003eThe microgel was formulated through the combination of Styrene (constituting the hydrophobic core), Acrylamide (forming the hydrophilic shell), N-vinyl-Ꜫ-caprolactam (contributing to the thermo-responsive shell), and (Hydroxyethyl)methacrylate (serving as the crosslinking agent). Various grades of microgels were synthesized using free radical emulsion solution polymerization techniques. In a 500 mL RB flask, 49.20 mM of Styrene and 39.3 mM of Acrylamide were combined, while the quantities of N-vinyl-Ꜫ-caprolactam and varied according to the grades (summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The reaction mixture underwent a 30-minute nitrogen gas purge at room temperature, followed by the addition of 500 mg of SDS and the gradual pouring of 250 mL of Millipore water under N\u003csub\u003e2\u003c/sub\u003e purging. The RB flask was then placed in a preheated oil bath at 70 \u003csup\u003eo\u003c/sup\u003eC.\u003c/p\u003e \u003cp\u003eUpon reaching 70 \u003csup\u003eo\u003c/sup\u003eC, 0.259 mM of KPS initiator was injected into the RB flask under nitrogen flow, resulting in a white suspension after 50\u0026ndash;60 minutes. The reaction continued for 2 hours at the same temperature, followed by cooling the mixture to room temperature. Subsequent workup involved the use of acetone, filtration with a sintered funnel, and drying under a vacuum oven at 60 \u003csup\u003eo\u003c/sup\u003eC and 15 mm of Hg for 36 hours. Other grades were synthesized following the same procedure, with variations in the content of NVCL. The synthetic route of the microgel and detailed synthesis information are illustrated in Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSynthetic details of synthesized grade of microgel.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS. No.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMicrogel\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStyrene\u003c/p\u003e \u003cp\u003e(mM)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAM\u003c/p\u003e \u003cp\u003e(mM)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNVCL\u003c/p\u003e \u003cp\u003e(mM)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eHEMA\u003c/p\u003e \u003cp\u003e(mM)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eKPS\u003c/p\u003e \u003cp\u003e(mM)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eSDS\u003c/p\u003e \u003cp\u003e(mg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e% Yield*\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eG1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e49.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e39.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.259\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eG2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e49.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e39.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.259\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e94\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eG3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e49.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e39.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.259\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e\u003csup\u003e\u003cem\u003e*% Yield = (Wt. of Microgel/Wt. of Monomer + Wt. of Crosslinker) x 100\u003c/em\u003e\u003c/sup\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of CuO Nanoparticles\u003c/h2\u003e \u003cp\u003eCuO nanoparticles were synthesized by the precipitation technique. Took 2 g of CuSO\u003csub\u003e4\u003c/sub\u003e.5H\u003csub\u003e2\u003c/sub\u003eO in a 250 mL RB flask and added 100 mL of HPLC water. This mixture was heated along with stirring and then, added 1 g of SDS at 60\u003csup\u003eo\u003c/sup\u003eC and maintained the solution pH is 12, by the continuous pouring of 0.1 M NaOH solution dropwise. Afterwards, continued the reaction for 24 hrs. Subsequently, the precursor was collected and worked out with acetone then filtered \u0026amp; washed with C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003eOH: H\u003csub\u003e2\u003c/sub\u003eO (1:1) till pH changed from 14 to 7 and dried in vacuum oven at 60 \u003csup\u003eo\u003c/sup\u003eC for 24 hours in 15 mm of Hg. Then, the precursor calcined at 400\u003csup\u003eo\u003c/sup\u003eC for 4 hours. The yield % of CuO nanoparticles is 91.6%.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of G/CuO nanoparticles composites\u003c/h2\u003e \u003cp\u003eSynthesis of G/CuO nanoparticles composites were performed by Hydrothermal Method. Took 250 mL of RB flask and charged by 1 g of Gs with 200 mg of CuO NPs in 20 mL of DD water. The RB flask was placed on the stirrer for 20 minutes with N\u003csub\u003e2\u003c/sub\u003e purging. Afterwards, sonicated the reaction mixture for 5 minutes and then the solution was transferred in an autoclave at the temperature 160 \u003csup\u003eo\u003c/sup\u003eC for 4 h. Cooled the composite and worked out with methanol then filtered the precipitate, and dried in an oven at 50 \u003csup\u003eo\u003c/sup\u003eC for 24 h in 15 mm of Hg. The synthetic route of G@CuO composite is shown in Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eCharacterizations\u003c/h2\u003e \u003cp\u003eFourier Transform Infrared (FTIR) spectra of microgel and G@CuO composite were recorded on an ATR Thermo-Fisher Scientific-Nicolet iS5 instrument. Thermo-gravimetric analysis (TGA) of G and G@CuO composite was carried out on a TGA (TGA Q500, TA Instruments, USA) instrument operated in a temperature range from 35\u0026deg;C to 700\u0026deg;C with a scanning rate of 10\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e under nitrogen gas flow. Scanning Electron Microscope (SEM) imaging and EDX analysis of microgel and G@CuO composite were carried out on a Carl Zeiss model Ultra 55 microscope which was gold-coated before imaging in SEM. Transmission electron microscopy (TEM) studies of synthesized G and G@CuO composite were conducted on a JEOL (JEM Model No. F200) TEM machine at an accelerating voltage of 200 kV. The samples were prepared by placing a drop of ethanol dispersed polymers solution on carbon-coated copper (200 mesh) grids. Dynamic light scattering (DLS) Particle size measurements of ethanol dispersed samples (Microgel and G@CuO composite) were performed using a Zetasizer Nano S90 (Malvern Instruments, Germany) operating at a 4 mW He-Ne laser with 633 nm wavelength at 25 \u003csup\u003eo\u003c/sup\u003eC, 40 \u003csup\u003eo\u003c/sup\u003eC, and 60 \u003csup\u003eo\u003c/sup\u003eC. The powder x-ray diffraction patterns (XRD) of the microgel and G@CuO composite were collected in a Bruker D8 Advance powder diffraction apparatus. The membrane samples were placed on a glass slide, and the diffractograms were recorded with Cu Kα radiation (λ\u0026thinsp;=\u0026thinsp;1.5406 \u0026Aring;) operated at 40 kV and 30 mA current in the angular range (2θ) of 5\u0026ndash;60\u0026deg; at a scanning rate of 2\u0026deg;/minutes. UV-Vis spectrophotometer (Shimadzu UV- 2600) was performed for absorption spectra of Methylene Blue Dye removal. Among all synthesized grades, G3 and their composites were characterized.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eApplications\u003c/h2\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003eMethylene blue dye removal by G@CuO composites\u003c/h2\u003e \u003cp\u003eIn the study of Methylene Blue (MB) dye removal using G@CuO composites, various experimental steps were undertaken. The process involved taking 200 \u0026micro;L of MB solution (0.1 mg/mL) in a UV cuvette and introducing 10 mg of the composites. Different volumes from a stock solution of NaBH\u003csub\u003e4\u003c/sub\u003e (0.105 mM), specifically 100 \u0026micro;L, 200 \u0026micro;L, and 300 \u0026micro;L, were added to the mixture. The total volume in the UV cuvette was adjusted to 3 mL by incorporating distilled water. Subsequently, the removal of MB was examined and quantified through UV-Vis. spectroscopy and the absorption peak was used to estimation is 663 nm. The catalytic reduction performance of the synthesized grades, denoted as G1 to G3, was documented at temperatures of 25\u0026deg;C, 40\u0026deg;C, and 60\u0026deg;C. This comprehensive approach aimed to assess the efficiency of the G@CuO composites in catalyzing the reduction of Methylene Blue under varying conditions.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Result and Discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eSynthesis of microgels and G@CuO composites\u003c/h2\u003e \u003cp\u003eCore-shell type microgel was synthesized by free-radical emulsion solution polymerization techniques. Microgel core was developed by polystyrene and shell through PAM, PNVCL, and PHEMA. The shell has crosslinked with the help of PHEMA, the substituents group having alcohol functionality and it have participating in hydrogen bonding with other polar groups like as: amide of PNVCL and PAM of parallel polymer chains as well as its covalently bonded with polymer backbone of vicinity chains [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. The thermoresponsive properties of microgel have varied by feeding of PNVCL in three different grades (G1 to G3) of microgel. Different grades were synthesized by varying the amount of NVCL to moderate the materials thermo-responsive nature. The variation of grades has been done by the consideration of the ratio of hydrophobic and hydrophilic content of microgel with stability in aqueous medium. From G1 to G3 the hydrophilic feed increases, and it has favors monomer conversion with same initiator feeds of KPS, the results justified by % yield and G3 shows highest yield % i.e. 97%. The synthetic details are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The feed of PNVCL corresponds to thermoresponsive nature of microgel swelling and deswelling properties. From G1 to G3, the PNVCL content increases with respect to increases the swelling properties of microgel matrix and at higher temperature the microgel shell (PNVCL) is least interact with aqueous medium and deswelling more in ascending grades.\u003c/p\u003e \u003cp\u003eCuO nanoparticle was successfully synthesized by precipitation method using NaOH to completely convert into hydroxide precursor and then calcined the precursor into CuO nanoparticles forms. The main challenge is to stabilize the CuO nanoparticles in their native forms was achievable by immobilized in the thermoresponsive microgel matrix. The microgel hydrophilic shell of PAM, PNVCL and PHEMA polar groups are coordinated with CuO and stabilized into the matrix and deceased from the agglomeration and sedimentation process. All three grades of microgels were implemented for the synthesis of composites i.e, Microgel@CuO composites. The stability of nanoparticles in grades was interpreted by the catalytic performance of CuO nanoparticles by methylene blue dye reduction graphs. In all grades got the approximately same yield % i.e. ~ 96%.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003eFTIR\u003c/h2\u003e \u003cp\u003eFTIR spectra of G3 and G3@CuO composite are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. In FTIR spectra of G3, the peak at 3430 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e appeared the of asymmetric -NH stretching of PAM and PNVCL. The peak at 1600 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponds to combination of Amide I and II stretching of PAM and PNVCL, and -CO of PHEMA. The characteristics -CH stretching of polymer backbone was attributed at 2930 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Peaks appeared at 1450 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1121 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in microgel representing the combination of aromatic C\u0026thinsp;=\u0026thinsp;C (polystyrene) and \u0026ndash;CH\u003csub\u003e2\u003c/sub\u003e vibrations, and -C-O stretching respectively.\u003c/p\u003e \u003cp\u003eIn FTIR spectra of G3@CuO composites, the stretching peak of amide 1 and amide II was shifted from 1600 to 1628 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e confirmed the bonding of CuO nanoparticles with polar amide group and it showed the CuO nanoparticle coordinated with the lone pair of nitrogen. The remaining peaks were the same as in microgel. The observed characteristic IR stretching and shifting confirmed the synthesis of microgel and composite.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eXRD\u003c/h2\u003e \u003cp\u003eXRD pattern of the copper nanoparticles is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. In the XRD analysis of the microgel, there is only one hump was depicted 2θ value of 19.09⁰ and no crystalline peak was observed. Thus, microgel is amorphous structure and they were no unreacted monomer was present. In composites, the characteristics CuO nanoparticles planes (110), (002), (111), (200), and (220) were observed at 35.47\u0026deg;, 38.97\u0026deg;, 43.4\u003csup\u003eo\u003c/sup\u003e, 50.4\u003csup\u003eo\u003c/sup\u003e, and 74.2\u003csup\u003eo\u003c/sup\u003e respectively. It indicates the CuO has monoclinic phase and JCPDS no. is 48-1548. The average crystallite size (t) has been calculated from the line broadening using Scherrer\u0026rsquo;s relation:\u003c/p\u003e \u003cp\u003et\u0026thinsp;=\u0026thinsp;0.89λ /Bcosθ\u003c/p\u003e \u003cp\u003ewhere λ is the wavelength of X-ray, B is the full width of half maximum (FWHM) and θ is the diffraction angle. The average crystallite size of CuO nanoparticles was calculated frompeak at θ\u0026thinsp;=\u0026thinsp;50.4\u003csup\u003eo\u003c/sup\u003e, is found to be 18.8 nm [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. XRD graph of microgel and composites are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eTGA Studies\u003c/h2\u003e \u003cp\u003eTGA pattern of G3 and G3@CuO composite is attribute in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. TGA analysis shows that G3 are thermally stable or working temperature below 370 \u003csup\u003eo\u003c/sup\u003eC. In the initial step the weight loss was observed at 100\u003csup\u003eo\u003c/sup\u003eC due to loss of moisture content of gel and the % weight is 2.13%. The second weight loss was observed at 365 \u003csup\u003eo\u003c/sup\u003eC due to the loss of cross-linking of G3 shell and % weight is 8.32%. The glass transition temperature (T\u003csub\u003eg\u003c/sub\u003e) of G3 is 410 \u003csup\u003eo\u003c/sup\u003eC and it was acheievd after the breaking of crosslinking in the matrix. Afterwards, at 441\u003csup\u003eo\u003c/sup\u003eC, completely burnout the gel and only 2.5% residue was left.\u003c/p\u003e \u003cp\u003eIn G3@CuO composite, the moisture content was less than microgel i.e. 0.74%. In next step the crosslinking was vanished at 374 \u003csup\u003eo\u003c/sup\u003eC and the % weight loss is 7.47%. The T\u003csub\u003eg\u003c/sub\u003e value of composite is 427 \u003csup\u003eo\u003c/sup\u003eC. At 455 \u003csup\u003eo\u003c/sup\u003eC, the composite lost their polymer matrix and only the carbon rsidue and nanoparticles were left and the combine % weight is 24.53%.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn all thermal weight loss stage the composite was found thermally more stable than microgel due to the CuO nanoparticles bound with the matrix polar group and provide rigidity which protect themselves from thermal vibrations. Hence, composite is thermally more stable than microgel matrix.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eDynamic Light Scattering Analysis\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(A to C) and 4(D to F) show the hydrodynamic diameter of G3 and G3@CuO composite at 25 \u003csup\u003eo\u003c/sup\u003eC, 40 \u003csup\u003eo\u003c/sup\u003eC, and 60 \u003csup\u003eo\u003c/sup\u003eC. Dynamic light scattering exhibited a particle size distribution of G3 is 1919 nm, 1477 nm, and 833 nm at 25\u003csup\u003eo\u003c/sup\u003eC, 40\u003csup\u003eo\u003c/sup\u003eC, and 60\u003csup\u003eo\u003c/sup\u003eC respectively. G3@CuO composite particle size exhibited a distribution of 1868 nm, 1070 nm and 716 nm at 25 \u003csup\u003eo\u003c/sup\u003eC, 40 \u003csup\u003eo\u003c/sup\u003eC, and 60 \u003csup\u003eo\u003c/sup\u003eC respectively. DLS analysis confirmed that in comparison to composite, microgel has more labile matrix in aqueous medium and it swells more. While increasing the temperature, both materials show excellent thermo-responsive and shrink their hydrodynamic diameter. These results confirmed that the bonded CuO nanoparticles decrease the number of available polar substituents to perform physiochemical interaction with the medium. Thus, the microgel and composite shows the excellent thermoresponsive behavior and the CuO nanoparticles successfully embedded in matrix in a stable form.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eScanning Electron Microscopy (SEM) Studies\u003c/h2\u003e \u003cp\u003eThe surface morphology of G3 and G3@CuO composite were obtained by SEM analysis shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e(A) \u0026amp; 5(B) respectively. SEM image of microgel shows spherical shapes scattered morphology and particle size varying from 0.5 to 2 \u0026micro;m. In the composite SEM image, the spherical structures have the same particle size range, but the spherical structure is rougher, more textured and spindle shape was observed due to incorporation of CuO nanoparticles. The change of surface morphology confirmed that the Cu-NPs were successfully encapsulated in a microgel structure.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eTransmission Electron Microscopy (TEM)\u003c/h2\u003e \u003cp\u003eThe shape and size of G3 and G3@CuO composite were obtained by TEM analysis shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e(A) and 6(B). TEM image of microgel confirmed the formation of spherical shape and its size ranges between 100\u0026ndash;200 nm. In the composite image, the microgel shape and size range is the same and the black dots represent the CuO-NPs 14 to 34 nm. TEM analysis confirmed the uniform distribution of NPs in microgel.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eEDAX\u003c/h2\u003e \u003cp\u003eHere, Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows the qualitative and quantitative EDAX analysis of microgel and nanocomposites. From the EDAX image of microgel, it was clear that only C and O peaks were observed and in nanocomposites, a Cu peak was also observed.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEDAX analysis of microgel and composite.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS. No.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMaterial\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eElement\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWeight %\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAtomic %\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMicrogel\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCK\u003c/p\u003e \u003cp\u003eNK\u003c/p\u003e \u003cp\u003eOK\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e86.47\u003c/p\u003e \u003cp\u003e1.04\u003c/p\u003e \u003cp\u003e12.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e89.39\u003c/p\u003e \u003cp\u003e0.92\u003c/p\u003e \u003cp\u003e9.70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMicrogel _Cu Composites\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCK\u003c/p\u003e \u003cp\u003eNK\u003c/p\u003e \u003cp\u003eOK\u003c/p\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e58.23\u003c/p\u003e \u003cp\u003e0.33\u003c/p\u003e \u003cp\u003e21.32\u003c/p\u003e \u003cp\u003e20.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e74.35\u003c/p\u003e \u003cp\u003e0.36\u003c/p\u003e \u003cp\u003e20.44\u003c/p\u003e \u003cp\u003e4.86\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn Table-3, the quantitative analysis of microgel was observed that C, N, and O have weight % is 6.47, 1.04, and 12.49%, and atomic % is 89.39, 0.92, and 9.70% respectively. In composite, weight % of C, N, O and Cu is 58.23, 0.33, 21.32 and 20.12% and atomic % is 74.35, 0.36, 20.44 and 4.86% respectively. EDAX analysis confirmed that Cu NPs successfully encapsulated in microgel structure.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eApplications\u003c/h2\u003e \u003cp\u003e \u003cstrong\u003eCatalytic activity\u003c/strong\u003e \u003cp\u003eThe catalytic activity of composites was recorded in respect of MB dye reduction by NaBH\u003csub\u003e4\u003c/sub\u003e as a reducing agent. The UV-Vis. spectra of all grades at room temperature (25 \u003csup\u003eo\u003c/sup\u003eC), 40 \u003csup\u003eo\u003c/sup\u003eC and 60 \u003csup\u003eo\u003c/sup\u003eC respective of different doses of NaBH\u003csub\u003e4\u003c/sub\u003e was recorded with Pseudo first order plots and depicted in Figs.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, 10 and \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e11\u003c/span\u003e respectively. Negative of the slope of the graph plotted between lnA\u003csub\u003et\u003c/sub\u003e/A\u003csub\u003eo\u003c/sub\u003e vs time gives the value of k\u003csub\u003eapp\u003c/sub\u003e, and the corresponding values are given in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The catalytic reduction of MB dye has been studied by all the grades with different doses of NaBH\u003csub\u003e4\u003c/sub\u003e varying the time at particular temperature. The nanocomposites have thermoresponsive behavior and it helps to control the catalytic reduction performance of CuO nanoparticles. The CuO nanoparticles have embedded on the thermoresponsive shell matrix which having the PNVCL chain, in above than moderate temperature 40 \u003csup\u003eo\u003c/sup\u003eC the caprolactam ring plays a thermal vibration and these could be restricted the interaction of shell with medium and the shell porous nature going to shrink. Thus, the CuO nanoparticles do not easily participate with the contaminated medium at higher temperature. Thus, this reduce the catalytic performance of nanoparticles at higher temperatures. In the kinetic studies of catalytic reduction of MB dye through the composites, the k\u003csub\u003eapp\u003c/sub\u003e was determined by the pseudo first order reaction, in which the dye and composites content is fixed and varied the NaBH\u003csub\u003e4\u003c/sub\u003e doses. In which, the k\u003csub\u003eapp\u003c/sub\u003e was highest at 200 \u0026micro;l (0.105 mM of NaBH\u003csub\u003e4\u003c/sub\u003e) and the lower doses are not sufficient to the reduction or higher doses are not diffused to complete the reduction with higher rate. Temperature effect plays an important role in MB reduction by composites at room and moderate temperature the k\u003csub\u003eapp\u003c/sub\u003e value is almost the same but at higher temperature its dramatically reduced to become inactive in catalytic reduction.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ek\u003csub\u003eapp\u003c/sub\u003e values in MB reductions in presence of the G1@CuO, G2@CuO and G3@CuO grades.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eGrade\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eK\u003csub\u003eapp\u003c/sub\u003e values (Sec. \u003csup\u003e\u0026minus;1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTemperature\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100 \u0026micro;L NaBH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e200 \u0026micro;L NaBH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e300 \u0026micro;L NaBH\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG1@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eRoom temperature (25 \u003csup\u003eo\u003c/sup\u003eC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG2@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG3@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.33\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG1@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e40 \u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG2@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.66\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG3@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG1@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e60 \u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG2@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.19\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eG3@CuO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIt was observed that k\u003csub\u003eapp\u003c/sub\u003e value increases from G1@CuO to G3@CuO in all the respective doses of NaBH\u003csub\u003e4\u003c/sub\u003e and temperature. From G1@CuO to G3@CuO the PNVCL content favors the catalytic performance with stability and is determined the k\u003csub\u003eapp\u003c/sub\u003e values.\u003c/p\u003e \u003cp\u003eHence, The G3@CuO shows excellent catalytic performance in moderate dose of NaBH\u003csub\u003e4\u003c/sub\u003e at room temperature with the highest k\u003csub\u003eapp\u003c/sub\u003e value of 1.87 Sec.\u003csup\u003e\u0026minus;1\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe thermoresponsive core-shell microgel was successfully synthesized by the free radical solution polymerization technique using polystyrene hydrophobic core and PAM, PNVCL and HEMA based hydrophilic shell. The developed microgel was established the crosslinking in shell by using the PHEMA content. The structure was confirmed by the FTIR techniques in which the characteristic stretching of all the content established the conclusion. The thermal studies confirm the materials are stable up to 360 \u003csup\u003eo\u003c/sup\u003eC and in comparison, to microgel composites are more stable. In the DLS analysis confirmed the deswelling and swelling properties of microgel and composites and it also depicts the negative thermoresponsive nature of microgel and composite. When the temperature rises the microgel and composite are de-swell. The electronic micrographs also confirmed the change in surface morphology between microgel and composites and attributed the size and shape of microgel and composites. The XRD analysis shows the amorphous nature of microgel and semicrystalline nature of composites. It confirmed the monoclinic phase of CuO nanoparticles and found the size range of nanoparticles in composite is ~\u0026thinsp;18.8 nm. The catalytic reduction of MB dye was estimated by using different parameters like temperature and NaBH\u003csub\u003e4\u003c/sub\u003e doses and the kinetic studies followed the pseudo first order reaction. The k\u003csub\u003eapp\u003c/sub\u003e value confirmed the catalytic performance of composite was performed well at moderate NaBH\u003csub\u003e4\u003c/sub\u003e dose at 40 \u003csup\u003eo\u003c/sup\u003eC. The composite shows inactivity at higher temperatures in catalytic reduction of MB dye due to their thermoresponsive nature. So, the synthesized catalyst worked in low concentrations of NaBH\u003csub\u003e4\u003c/sub\u003e at normal temperature and checked the catalytic reaction at higher temperatures. The key role of catalyst to switch the catalytic reaction by varying the temperature of medium. This is the potential candidate to use in the treatment of industrial wastewater at low cost.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was financially supported by the Science Engineering and Research Board (TAR/2020/000351), New Delhi, Government of India.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of interest Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eZheng C, Lian D, Chang S, Ma C, Du M, Sun X (2017) Treatment of dye wastewater nanofiltration concentrates containing high anion levels by a pH-sensitive nano-sized Fe(iii)@silica microgel. 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Soft Matter18(3): 535-544.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u0026nbsp;Siddiqui H, Parra MR, Qureshi MS, Malik MM, Haque FZ (2018) Studies of structural, optical, and electrical properties associated with defects in sodium-doped copper oxide (CuO/Na) nanostructures. J of mate sci 53(12): 8826-8843.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme","content":"\u003cp\u003eScheme 1 and 2 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Core-Shell Microgel, Catalysis, Emulsion Polymerization, Thermoresponive Polymer, CuO nanoparticles","lastPublishedDoi":"10.21203/rs.3.rs-3858144/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3858144/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe present study details the catalytic reduction of water pollutants (Methylene blue). In this research, the synthesis of microgels was achieved through free-radical emulsion polymerization techniques employing HEMA monomer as a crosslinker. Three different grades of microgel have synthesized by varying the amount of N-vinyl caprolactam. Copper-oxide nanoparticles were successfully incorporated into polymeric microgels through hydrothermal methods for catalytic reduction applications. Characterization of both microgels and microgel-nanoparticle composites was conducted using various techniques like as: Fourier transform infrared spectroscopy (FT-IR), powder X-Ray diffraction (Powder XRD) Dynamic light scattering (DLS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The catalytic reduction of methylene blue (MB) was characterized using ultraviolet-visible spectrometry. The catalytic reduction efficiency of the dye was measured by optimizing the parameter effect of crosslinking, temperature responsive monomer feed, temperature and amount of reducing agent (NaBH\u003csub\u003e4\u003c/sub\u003e). Microgel nanocomposites respond to efficient catalysis at higher NVCL feed with moderate dose of NABH\u003csub\u003e4\u003c/sub\u003e.\u003c/p\u003e","manuscriptTitle":"Fabrication of Low Cost Thermoresponsive Microgel@CuO Catalyst for Rapid Reduction of Methylene Blue Dye","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-02-09 20:41:29","doi":"10.21203/rs.3.rs-3858144/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-02-13T20:16:02+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-02-06T03:22:58+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Journal of Polymer Research","date":"2024-01-17T20:17:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-01-15T06:37:49+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Polymer Research","date":"2024-01-12T13:55:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5947ee58-6461-4913-bd95-ea9224c11d3a","owner":[],"postedDate":"February 9th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-06-21T15:28:07+00:00","versionOfRecord":{"articleIdentity":"rs-3858144","link":"https://doi.org/10.1007/s10965-024-04022-3","journal":{"identity":"journal-of-polymer-research","isVorOnly":false,"title":"Journal of Polymer Research"},"publishedOn":"2024-06-01 15:28:07","publishedOnDateReadable":"June 1st, 2024"},"versionCreatedAt":"2024-02-09 20:41:29","video":"","vorDoi":"10.1007/s10965-024-04022-3","vorDoiUrl":"https://doi.org/10.1007/s10965-024-04022-3","workflowStages":[]},"version":"v1","identity":"rs-3858144","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3858144","identity":"rs-3858144","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}