Massively Preparable, Super-tough and Ultra-strong Cellulose-based Bioplastics Enabled by Microphase Separation

Massively Preparable, Super-tough and Ultra-strong Cellulose-based Bioplastics Enabled by Microphase Separation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Massively Preparable, Super-tough and Ultra-strong Cellulose-based Bioplastics Enabled by Microphase Separation Weifu Dong, Xuhui Zhang, Bohan Lv, Chongyang Li, Hang Chen, Chunyi Gu, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7148129/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The growing environmental concern over petroleum-based plastics have promoted the exploration of sustainable bioplastics with competitive properties. Cellulose is an ideal sustainable alternative with endless sources and biodegradability, but poor processability and poor toughness severely restrict their practical applications. Herein, a microphase separation strategy is proposed to massively prepare super-tough and ultra-strong cellulosic plastics. The microphase separation is realized by thermoplastic processing and water-soaking process, highlighting the potential of large-scale preparation. The combined microphases (100 ~ 300 nm) and rigid continuous phase enable a tensile strength of 147.6 ± 9.6 MPa and a toughness of 30.2 ± 2.1 MJ/m 3 , where numerous microphases play a unique toughening role via forcing the movement of rigid chain-segments. Besides, the microphase-separated cellulosic plastics possess excellent UV-shielding effect, good transparency, high glass transition temperature, high decomposition temperature and good solvent resistance, stressing the excellent comprehensive properties and wide applicability. The combined large-scale preparation and excellent comprehensive properties are unprecedented for cellulosic plastics. This work provides a novel yet facile microphase separation strategy to prepare high-performance cellulosic plastics, and will promote the substitution of petroleum-based plastics by sustainable cellulosic plastics with endless sources. Physical sciences/Materials science/Structural materials/Mechanical properties Physical sciences/Materials science/Techniques and instrumentation/Design, synthesis and processing Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Plastics have been one of the cornerstones of human civilization due to its indispensability in industry and daily life. To date, over 8 billion tons of plastics have been produced globally. [ 1 ] However, the wide use of plastics has seriously exacerbated the petroleum depletion and environmental pollution since most plastics are derived from non-renewable petroleum resources and hard to degrade. Under this background, bio-based plastics with good sustainability have attracted extensive attention from both the academia and industry in recent years. [ 2 ] Although bio-based polyesters represented by polylactic acid (PLA), polybutylene succinate (PBS) and polyhydroxyalkanoate (PHA) have received increasing attention, they cannot meet the actual demands due to the low production and inadequate properties. [ 3 – 5 ] Besides, starch-based plastics are sustainable plastics with high availability, high production and low cost, but their practical applications are severely limited by problems such as poor mechanical properties, high sensitivity to humidity and competition with humans for food sources. [ 6 ] Therefore, developing bio-based plastics with endless non-food sources and competitive properties are urgently pursued. Cellulose is the most abundant biopolymer on the earth with merits of endless non-food sources, high modulus, high strength and biodegradability, suggesting that it is an ideal alternative to replace petroleum-based plastics. [ 7 , 8 ] However, due to the rigid backbone, the highly ordered structure and the high-density hydrogen bonding (H-bond), native celluloses show poor solubility in common solvents and poor thermoplastic processability, leading to the poor processability. [ 9 ] With the aid of special solvents (such as NaOH/urea, LiOH/urea and ionic liquids), native cellulose can be dissolved and molded by casting. [ 10 , 11 ] Nevertheless, these regenerated celluloses are very brittle due to the lack of chain-segment movability, leading to very limited practical applications. [ 10 , 11 ] Grafting aliphatic side chains onto cellulose can consume hydroxyl groups, weaken intermolecular H-bond and increase intermolecular distance, enabling the improved chain-segment movability, processability and toughness of cellulose derivatives. [ 12 ] However, the rigid backbone still makes it difficult for cellulose derivatives to be directly melt-blended or exhibit high toughness, unless a suitable plasticizer is introduced. [ 13 , 14 ] In this case, plasticizers will significantly sacrifice the attractive high strength and high modulus of celluloses and result in the high sensitivity to moisture. [ 13 , 14 ] Although cellulose nanopapers prepared by filtrating cellulose nanofibers’ aqueous dispersion [ 15 , 16 ] and cellulose-based composites with "brick-mortar" structure [ 17 , 18 ] can show great tensile strength (above 200 MPa), they still suffer from poor toughness and low processing efficiency. Therefore, preparing strong and tough cellulose-based plastics via a large-scale method is still challenging. In this work, a microphase separation strategy is proposed to prepare super-tough and ultra-strong cellulose-based plastic via a large-scale manner. Via soaking crosslinked hydroxyethyl cellulose (HEC) containing dimethyl sulfoxide (DMSO) into water, a unique water-mediated microphase separation occurs, enabling the formation of plentiful small-sized hydrophobic microphases (100 ~ 300 nm) into rigid HEC continuous phase. These microphases can serve as multifunctional phases to toughen HEC, improve the water resistance, shield ultraviolet light with short-wavelength and let through visible light with long wavelength. Consequently, the microphase-separated HEC (Sep-HEC) shows charming mechanical properties (a tensile strength of 147.6 ± 9.6 MPa and a toughness of 30.2 ± 2.1 MJ/m 3 ), excellent optical properties (combined UV-shielding and transparency), good solvent resistance and excellent heat resistance. Moreover, the microphase separation is realized by thermoplastic processing and water-soaking process, highlighting the potential of large-scale preparation. The unprecedented combining of large-scale preparation and excellent comprehensive properties will promote the substitution of petroleum-based plastics by sustainable cellulosic plastics with endless sources. Results Preparation and Characterization of the Sep-HEC The preparation process of Sep-HEC consists of two steps, namely preparing crosslinked HEC with DMSO and inducing microphase separation of the crosslinked HEC by water. As shown in Fig. 1 , acrylated HEC (A-HEC) is firstly prepared by grafting methacryloyloxyethyl isocyanate (MOI) onto DMSO-plasticized HEC based on nucleophilic addition reaction between hydroxyl group and isocyanate. Subsequently, the A-HEC was crosslinked by pentaerythritol tetra(3-mercaptopropionate) (PETMP) based on thia-Michael reaction between thiol and acrylate to generate a crosslinked HEC (C-HEC) containing DMSO. [ 19 ] Then the C-HEC containing DMSO is immersed in water to leach out DMSO, during which the C-HEC undergoes microphase separation due to the aggregation of adjacent hydrophobic crosslinked structures and the self-assembling of HEC chains with dense H-bond, generating a Sep-HEC with water. After drying, the Sep-HEC is obtained. Samples with fixed DMSO content (equal to the HEC weight) and variable crosslinker contents are nominated as ‘Sep-HEC-Mx/Py’, where Mx represents the molar percentage (mol%) of MOI to the hydroxyl groups in HEC while Py represents the mol% of thiol in PETMP to the hydroxyl groups in HEC. Samples with fixed crosslinker content (M2 and P2) and variable DMSO contents are nominated as ‘Sep-HEC-DMSOz’, where z represents the weight percentage (wt%) of DMSO to HEC. Sep-HEC-DMSO300, a Sep-HEC with a high HEC content of 94 wt%, is selected as a represent. Photos shows its high transparency and excellent flexibility (Fig. 1 B). The stress-strain curve displays the ultra-high tensile strength (σ) of 147.6 ± 9.6 MPa and the high elongation at break (ε) of 30.9 ± 1.8% (Fig. 1 C), enabling a remarkable toughness (as indicated by the work to failure of per unit volume) of 30.2 ± 2.1 MJ/m 3 . Besides, Sep-HEC-DMSO300 also possesses excellent ultraviolet shielding effect (about 90%, Figure S1 ), high decomposing temperature (T d,max =377 o C, Figure S2 ) and high T g (167.9 o C, Figure S3 ). Compared with some representative commercial plastics, such as general plastic polystyrene (PS), engineering plastic polycarbonate (PC) and bio-based plastic poly(lactic acid) (PLA), the Sep-HEC-DMSO300 shows great superiority in terms of mechanical properties, thermal properties and UV-shielding properties (Fig. 1 D), suggesting the great potential to replace traditional plastics. The successful graft of MOI onto HEC is verified by FTIR spectra, where characteristic peaks of MOI, including C = O (1720 cm⁻¹), C = C (1634 cm⁻¹) and C-O-C (1156 cm⁻¹), can be clearly observed in A-HEC ( Figure S4 ). In Figure S5 , characteristic peak of thiol (2570 cm − 1 ) in PETMP and C = C (1634 cm − 1 ) in A-HEC disappear in the C-HEC while characteristic peak of C = O (1728 cm − 1 ) in PETMP is observed in the C-HEC, demonstrating the occurrence of thia-Michael reaction convincingly. Besides, the insolubility of C-HEC in DMSO ( Figure S6 ) and the high gel content (> 78%) of various C-HECs ( Figure S7 and S8 ) verify the crosslinked structure of C-HEC. Interestingly, increasing the crosslinker content doesn’t increase the gel content of C-HEC obviously ( Figure S7 ) while increasing the DMSO content does ( Figure S8 ). This is due to the macroscopically uniform but microscopically non-uniform dispersion of the crosslinkers, which is caused by the limited content of DMSO and the high viscosity of the plasticized HEC. Thus, increasing DMSO content can effectively reduce the viscosity of plasticized HEC and optimize the dispersion of crosslinkers, thereby increasing the gel content. This result also indicates the non-uniformity of the crosslinked structure at microscopic level. Notably, DMSO can be both a highly efficient plasticizer for HEC and a solvent for MOI and PETMP while the employed reactions can be realized efficiently under mild conditions. Therefore, the plasticization, modification and crosslinking can be achieved by thermoplastic processing which is easy to scale. The C-HEC containing DMSO possesses high chain-segment movability and thermodynamically incompatible structures (the crosslinking point and the HEC chain-segment away from crosslinking point), enabling the water-mediated microphase separation where thermodynamically compatible structures aggregate and incompatible structures separate. [ 20 , 21 ] The high chain-segment movability of C-HEC containing DMSO, which is enabled by the plasticizing effect of DMSO, is evidenced by the low T g ( Figure S9 ) and the low young’s modulus (550 ± 32 kPa) ( Figure S10 ). To reveal the water-mediated microphase separation, the Sep-HEC-M2/P2 with water was freeze-dried (Sep-HEC-M2/P2-FD) and the condensed-state structures was investigated. SEM image of Sep-HEC-M2/P2-FD reveals the interconnected skeleton and lots of large pores (dozens of microns), where the skeleton contains plentiful small microphases (100 ~ 200 nm) (Fig. 2 A). These large pores should relate to water-rich regions, and should originate from the sparsely crosslinked domains with high hydrophilicity and less covalent linkages. The skeleton should originate from the highly crosslinked regions with improved hydrophobicity and more covalent linkages. These microphases in skeleton should root from the aggregation of adjacent hydrophobic crosslinked structures under water stimulation. For Sep-HEC-M2/P2 (Fig. 2 B), plentiful small microphases (100 ~ 300 nm) are observed while no large pores are observed, suggesting the remaining of the microphase and the densification of HEC chains during the thermal drying. In the tanδ-T relationship curves (Fig. 2 C), Sep-HEC-M2/P2-FD exhibits two glass transitions, namely a main peak around 161°C and a shoulder peak around 100°C, confirming the two-phase structure. The main peak should correspond to the continuous phase in the skeleton while the shoulder peak should relate to the microphase in the skeleton. The lower T g of microphase is due to the crosslinked structures which can consume hydroxyl groups and increase the interchain distance. For Sep-HEC-M2/P2, two glass transitions confirms the remaining of the microphase. Besides, the main glass transition shows a decreased intensity while the glass transition relating to microphase is enhanced and blurred when compared with Sep-HEC-M2/P2-FD, suggesting the increased interface layer which should originate from the densification of HEC chains around microphases during the thermal drying. Moreover, AFM micrographs further provide direct evidences for the microphase separation structure of Sep-HEC-M2/P2. As shown in Fig. 2 D and 2 E, a sea-island microphase separation structure is clearly observed, where the microphase shows a small size of 100 ~ 200 nm and a lower modulus than that of the continuous phase. Mechanical Properties of Sep-HECs. The mechanical properties of all samples are provided in Table S1 and Fig. 3 . Figure 3 A displays the stress-strain curves of casted HEC and Sep-HECs with various crosslinker contents. Both the σ and the ε of Sep-HECs are much higher than that of the casted HEC, demonstrating the great superiority of Sep-HECs in mechanical properties. For example, the casted HEC exhibits a σ of 19.8 ± 1.1 MPa and an ε of 9.3 ± 0.5% while Sep-HEC with a few crosslinkers (Sep-HEC-M2/P2) shows a σ of 100.1 ± 8.7 MPa and an ε of 39.4 ± 2.3%. Besides, increasing the crosslinker content can increase the ε but decrease the σ of Sep-HECs, notifying that the crosslinked structure mainly contributes to the high extensibility. Addition to the crosslinker content, DMSO content can also powerfully affect the mechanical properties of Sep-HECs. As shown in Fig. 3 B, compared to Sep-HEC-DMSO100, Sep-HEC-DMSO300 shows a greatly improved σ of 147.6 ± 9.6 MPa and a slightly decreased ε of 30.9 ± 1.8%, enabling a super toughness of 30.2 ± 2.1 MJ/m 3 . The excellent mechanical properties enable a small specimen (0.09 g) of Sep-HEC-M2/P2 to lift a weight of 6.0 kg which is more than 60000 times of the specimen’s weight (Fig. 3 C). Figure 3 D compares the σ and toughness of the as-fabricated Sep-HECs and some representative cellulose-based plastics. Although regenerated cellulose films exhibit high σ above 100 MPa, the low ε leads to the poor toughness below 6 MJ/m 3 . [ 22 – 24 ] Cellulose nanopapers prepared from cellulose nanofibers can show ultra-high σ, and subtly designed microstructure structure enables a toughness above 10 MJ/m 3 . [ 25 – 28 ] However, the ε is still very limited, resulting in a toughness less than 13 MJ/m 3 . Chemical modification and incorporating plasticizers can effectively improve the ε of cellulose-based plastics, but the σ is sharply decreased and the ε is generally less than 80%, resulting in a limited toughness. [ 29 – 32 ] As a stark contrast, the as-fabricated Sep-HECs possess both high σ and high toughness. Particularly, Sep-HEC-DMSO300 shows a high σ of 147.6 ± 9.6 MPa and a super toughness of 30.2 ± 2.1 MJ/m 3 , which is unprecedented for cellulose-based plastics. Moreover, the σ of Sep-HEC-DMSO300 is much greater than most commercially available plastics while the toughness is superior to or comparable with them, highlighting the great potential to replace petroleum-based plastic (Fig. 3 D). To understand the mechanism for the excellent mechanical properties of Sep-HECs, the tensile-fractured surface of Sep-HEC-M2/P2 is firstly observed by SEM. In Fig. 4 A and 4 B, Sep-HEC-M2/P2 show a highly rough surface with obvious deformation of partial matrices, indicating a ductile fracture rooting from the motion of partial chain-segments. Meanwhile, some large-sized cracks are observed on the surface, which should be responsible for the fracture of the sample. Then the side view of Sep-HEC-M2/P2 with various strain are recorded. With 10% strain, plentiful small grooves perpendicular to the external force are observed around the microphase (Fig. 4 C and 4 D), suggesting that the microphase can act as stress concentration points to induce small microcracks. These microcracks should originate from the forced movement of partial chain-segments, and can arrest and dissipate energy. When the strain reaches the break strain (about 40%), the grooves become more obvious and some grooves are deflected (Fig. 4 E), suggesting the development of the microcracks and the rearrangement of partial HEC chains. The rearrangement of partial HEC chains will continuously dissipate energy, enabling the development of microcracks and inhibiting the quick transformation of microcracks into macrocracks. Meanwhile, some cracks parallel to the external force are also observed in Fig. 4 E, which should originate from the development of microvoids and be responsible for the fracture of the sample. Notably, although both microphases and microvoids can act as stress concentration points to induce microcracks, they show quite different effects. For microphases with small size and high quantity, they induce plentiful small-sized microcracks which can dissipate energy, promote the rearrangement of HEC chains and develop continuously during deformation, playing a toughening role. For microvoids with large size and small quantity (as revealed by Fig. 2 B), they induce a few large-sized microcracks which will develop into cracks and fracture the sample. In addition, although the contribution of a single microcrack to ε is very limited, plentiful microcracks enable a significantly improved ε. Therefore, the super toughness mainly roots from the plentiful microcracks induced by microphases, and the high content of microphases is vital for the high extensibility. Furthermore, the high strength of Sep-HEC-M2/P2 should originate from the glassy state of all chain-segments and the high rigidity of continuous phase, which are evidenced by the DMA results (Fig. 2 C and S11). Based on the above mechanism, we can well explain the mechanical behaviors of different Sep-HECs. Plentiful microcracks induced by numerous microphases enable the large ε (>30%) of all Sep-HECs. With a fixed DMSO content, increasing crosslinker content can increase the microphase content, leading to the improved ε and decreased σ. When the crosslinker content is fixed, increasing DMSO content can promote the moving and assembling of HEC chain-segments into a rigid skeleton, resulting in the reduced microphase content, decreased ε and increased σ. Optical, thermal and solvent-resistant properties of Sep-HECs. Sep-HECs show excellent UV-shielding effect while maintaining a good transparency. As shown in Fig. 5 A, casted HEC shows negligible UV-shielding effect. In sharp contrast, Sep-HECs exhibit excellent UV-shielding effect, and the effect is enhanced with the increment of crosslinker content. For instance, Sep-HEC-M2/P2 can effectively shield UV below 300 nm, while Sep-HEC-M6/P6 can shield all UV below 400 nm. Meanwhile, all Sep-HECs show good transparency as their transmittances at 550 nm are higher than 70%. The combined UV-shielding and high transparency should be attributed to the small-sized microphases which can strongly scatter UV light with short-wavelength and weakly scatter visible light with long-wavelength. Besides, Sep-HECs show high T g s with the value above 160 o C, suggesting the excellent dimensional stability at high temperature (Fig. 5 B). Sep-HECs also possess high decomposition temperature (T d ) with the starting T d above 310 o C and the fastest T d above 370 o C (Fig. 5 C and S12), indicating the good thermostability. Sep-HECs show good solvent resistance as well. As shown in Fig. 5 D, casted HEC shows a low water contact angle of 23 o while various Sep-HECs display high water contact angles above 80 o , suggesting the obviously improved hydrophobicity. Although casted HEC and Sep-HECs show weakened σ after being placed in an oven for 48h at 60 RH% and 25 o C due to the adsorption of water, Sep-HEC-M2/P2 possesses a high σ of 50.1 ± 2.8 MPa and a high ε of 76.8 ± 4.2% (Fig. 5 E), suggesting the applicability in high-humidity environments. After being soaked in different HCI solutions for 15 days and dried, Sep-HEC-M4/P4, a Sep-HEC with relatively high crosslinker content, shows similar stress-strain curves before and after soaking (Fig. 5 F), highlighting the excellent resistance to acid environment of Sep-HECs. Moreover, Sep-HEC-M4/P4 can well maintain its original shape after being soaked in common organic solvents, such as ethyl acetate, toluene and ether (Fig. 5 G). After being dried, these soaked Sep-HEC-M4/P4s exhibit mechanical properties comparable to the unsoaked sample (Fig. 5 H), notifying the excellent resistance to organic solvents. Discussion In summary, we successfully develop a cellulose-based plastic with super toughness, ultra-high strength and excellent comprehensive properties based on the water-mediated microphase separation strategy. Based on the unique toughening mechanism of small microphases (100 ~ 300 nm) via inducing plentiful small microcracks, the rigid Sep-HEC-DMSO300 shows both a charming tensile strength of 147.6 ± 9.6 MPa and a super toughness of 30.2 ± 2.1 MJ/m 3 , providing inspiration for the design of stiff and tough polymers. Besides, the microphase can strongly scatter UV light and weakly scatter visible light, enabling the excellent UV-shielding effect and good transparency of Sep-HEC. Moreover, the combined crosslinking structure, hydrophobic microphase and hydrophilic continuous phase impart Sep-HEC with good resistance to both water and organic solvent. The rigid backbone of HEC and decreased content of hydroxyl groups enable the high T g (≥ 160 o C) and high T d (T d, max ≥370 o C) of Sep-HEC. Furthermore, the microphase separation is achieved by thermoplastic processing and water-soaking process, highlighting the potential of large-scale preparation for the high-performance bioplastic. The combined large-scale preparation and excellent comprehensive properties are unprecedented for cellulose-based plastics, and will promote the substitution of petroleum-based plastics by cellulosic plastics with endless sources. Methods Materials . Hydroxyethyl cellulose (HEC) with a molar degree of substitution of 2.09 was purchased from Shandong YouSuo Chemical Technology Co., Ltd. Methacryloyloxyethyl isocyanate (MOI) was purchased from Shanghai Titan Technology Co., Ltd. Pentaerythritol tetra(3-mercaptopropionate) (PETMP) and dimethyl sulfoxide (DMSO) were purchased from Shanghai McLean Biochemical Technology Co., Ltd. Preparation of crosslinked HEC containing DMSO. Take crosslinked HEC-M2/P2 as an example, 25.0 g powdery HEC (0.3 mol hydroxyl group) and 15 g DMSO (60 wt% of HEC) were added into an internal mixer at 70°C and blended for 8 min to prepare plasticized HEC. Subsequently, 0.9 g MOI (6 mmol) in 5 g DMSO (20 wt% of HEC) was dropped into the internal mixer and reacted for 20 min at 70 o C under continuous blending. Then, 0.7 g PETMP (6 mmol thiol groups) in 5 g DMSO (20 wt% of HEC) was dropped into the internal mixer and reacted for 20 min at 70 o C under continuous blending. Then the blend was hot-pressed at 140 o C for 20 min to obtain the crosslinked HEC containing DMSO in the form of sheet. To regulate the crosslinking structure, the contents of MOI and thiol groups were designed as 2 mol%, 4 mol% and 6 mol% of hydroxyl group in HEC, with a fixed DMSO content of 100 wt% of HEC. Furthermore, the DMSO content was designed as 100 wt%, 200 wt% and 300 wt% of HEC to manipulate the movability of HEC chains, with a fixed MOI and thiol groups of 2 mol% of hydroxyl group in HEC. Preparation of Sep-HEC. The crosslinked HEC sheet containing DMSO was soaked into deionized water for 30 min and the soaking was repeated for 3 times to fully leach out DMSO and induce microphase separation. Then the sample after soaking was placed in a fume hood for 6 hours and dried in a vacuum oven at 60°C until constant weight to obtain the microphase-separated HEC-based plastic (Sep-HEC). Since HEC can solve in water, HEC film, a contrast sample, was prepared by casting HEC aqueous solution with a concentration of 1 w/v%. Characterization. The FTIR spectra were performed on a Nicolet iS50 FTIR spectrometer over the range of 400–4000 cm − 1 . The TGA curves were recorded by a TGA2 thermogravimetric analyzer in an N 2 atmosphere with a temperature range of 25–700 o C. The UV-Vis spectra were recorded by a TU-1950 UV-visible spectrophotometer over the range of 200–800 nm. The stress-strain curve was performed on an Al-7000-SU1 test tensile machine at room temperature with a tensile rate of 1 mm/min. The toughness, which is reflected by the work to failure of per unit volume of the sample, was calculated by integrating the stress-strain curve. At least 5 specimens were measured for each sample to ensure the accuracy and reproducibility of the data. SEM images were recorded by a HITACHI S-4800 scanning electron microscopy with an accelerated voltage of 1 kV. AFM images were recorded by a MuLtimode 8 atomic force microscope. The specimens for AFM measurement were prepared by freezing slice. The contact angle was recorded by a Theta Flow video-optical contact angle meter. DMA was performed on a DMA850 dynamic mechanical analyzer with a temperature range of 30–200 o C and a ramp rate of 3 o C/min. The gel content was measured by following the steps. The crosslinked HEC containing DMSO was completely dried firstly. Then specific content of sample (about 0.5 g) was weighed (m 0 ) and soaked in sufficient DMSO for 72 h under continuous slight oscillation. The DMSO was exchanged every 24 h to ensure the completely dissolving out of soluble portions. Then the residual gel was dried and weighed (m 1 ). The gel content was calculated by Eq. ( 1 ): $$\:\text{g}\text{e}\text{l}\:\text{c}\text{o}\text{n}\text{t}\text{e}\text{n}\text{t}\:\left(\text{%}\right)={m}_{1}/{m}_{0}\:\times\:100$$ 1 Declarations Conflict of Interest The authors declare no conflict of interest. Acknowledgment This work was supported by National Natural Science Foundation of China (52273089, 52303127). Data Availability All data required to assess the conclusions of this paper are included within the paper and the Supplementary Information. The data are available from the corresponding authors upon reasonable request. 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Guzman-Puyol. Int J Biol Macromol 273 Additional Declarations There is NO Competing Interest. Supplementary Files Supportinginformation.docx Supporting Information Graphicalabstract.docx Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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-7148129","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":497099033,"identity":"52cd7eb0-64e8-4bea-a08d-0e011d1c8f8a","order_by":0,"name":"Weifu Dong","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA80lEQVRIiWNgGAWjYDAC5gMGQNKGmQ0hlEBAC1sCSEsa6VoOIwsR0GJwjHnj44Jf59n52M8efl1Qc4eBnz3HgOHnDnxa2IqNZ/bdZmbjyUuznnHsGYNkzxsDxt4zuLWY3e8xk+btAWphyDEz5mE7zGBwI8eAmbENj5ZjPCAt55jZ+N8Atfw7zGBPlBaeHweY2SRyjB/ztgFtkSCgxR7kF96GZKCWN2bMvH2HeSTOPCs42ItHi2QbMMR4/tgly/fnGH/m+XZYjr89eeODn3i0gAHQGclAik0CSPCABA4Q0AAEfxjsgCTzB8IqR8EoGAWjYCQCAB5oStNP4+/9AAAAAElFTkSuQmCC","orcid":"","institution":"Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":true,"prefix":"","firstName":"Weifu","middleName":"","lastName":"Dong","suffix":""},{"id":497099034,"identity":"683b4d47-389b-4d63-83d4-4bd15d3546ff","order_by":1,"name":"Xuhui Zhang","email":"","orcid":"","institution":"School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Xuhui","middleName":"","lastName":"Zhang","suffix":""},{"id":497099035,"identity":"b27ba67d-d207-4d65-990d-b41170a61ac2","order_by":2,"name":"Bohan Lv","email":"","orcid":"","institution":"School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Bohan","middleName":"","lastName":"Lv","suffix":""},{"id":497099036,"identity":"f0a47041-7773-44c3-ad93-be2eafc418cb","order_by":3,"name":"Chongyang Li","email":"","orcid":"","institution":"School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Chongyang","middleName":"","lastName":"Li","suffix":""},{"id":497099037,"identity":"ca40bc52-52aa-4c21-9412-7b5201f52472","order_by":4,"name":"Hang Chen","email":"","orcid":"","institution":"School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Hang","middleName":"","lastName":"Chen","suffix":""},{"id":497099038,"identity":"36599cd4-479d-4c34-b1ce-1d66d09cf497","order_by":5,"name":"Chunyi Gu","email":"","orcid":"","institution":"School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Chunyi","middleName":"","lastName":"Gu","suffix":""},{"id":497099039,"identity":"1e897258-a18e-4a9b-9cff-7631564f1bfe","order_by":6,"name":"Jing Huang","email":"","orcid":"","institution":"School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Jing","middleName":"","lastName":"Huang","suffix":""},{"id":497099041,"identity":"8f7fe300-4aff-4226-a452-c5d4fed580ac","order_by":7,"name":"Ting Li","email":"","orcid":"","institution":"Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Ting","middleName":"","lastName":"Li","suffix":""},{"id":497099043,"identity":"d90d2702-12c6-49b5-9f05-5f970e4fab48","order_by":8,"name":"Shibo Wang","email":"","orcid":"","institution":"School of Chemical and Material Engineering, Jiangnan University","correspondingAuthor":false,"prefix":"","firstName":"Shibo","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2025-07-17 10:40:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7148129/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7148129/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":89375293,"identity":"a987a45a-976e-4f5a-9735-fd851523ccfb","added_by":"auto","created_at":"2025-08-19 10:54:17","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":125913,"visible":true,"origin":"","legend":"\u003cp\u003eStructural design and key features of Microphase-separated Cellulose-Based Plastics (Sep-HEC). (A) Schematic illustration of the preparation process and relating microstructure of Sep-HEC. (B) Photos of Sep-HEC to show the high transparency and excellent flexibility. (C) Stress-strain curves of casted HEC and Sep-HEC. (D) Radar chart to compare Sep-HEC with commercially available plastics including general plastic PS, engineering plastic PC and bio-based plastic PLA.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/b5559eb3968ca8dc012d5215.jpg"},{"id":89375295,"identity":"ec891b9a-9229-4f72-81f2-b7cb8d037148","added_by":"auto","created_at":"2025-08-19 10:54:17","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":152275,"visible":true,"origin":"","legend":"\u003cp\u003eEvidences for the water-mediated microphase separation of crosslinked HEC containing DMSO. (A, B) SEM images of Sep-HEC-M2/P2-FD and Sep-HEC-M2/P2. (C) The relationship curves between tanδand temperature for Sep-HEC-M2/P2-FD and Sep-HEC-M2/P2. (D, E) Representative height micrograph and DMT modulus micrograph of the Sep-HEC-M2/P2 recorded by AFM.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/30970252323d034dc5f01b71.jpg"},{"id":89375294,"identity":"f019b2eb-9904-41e3-b8bd-ad52990ff2c8","added_by":"auto","created_at":"2025-08-19 10:54:17","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":111979,"visible":true,"origin":"","legend":"\u003cp\u003eMechanical properties of Sep-HEC. (A) Stress-strain curves of Sep-HECs with various crosslinker contents. (B) Stress-strain curves of Sep-HECs prepared with various DMSO contents. (C) The photo of a small Sep-HEC-M2/P2 specimen (0.09 gram) bearing an object of 6 kilograms. (D) The comparison of the σ and toughness for the as-fabricated Sep-HEC and some representative cellulose-based plastics. (E) The comparison of the σ and toughness for the Sep-HEC-DMSO300 and some commercially available plastics.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/1c6dbd4fc975fdfb1350e71c.jpg"},{"id":89375813,"identity":"b133654e-722a-4c63-92fe-de26628de85d","added_by":"auto","created_at":"2025-08-19 11:02:17","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":150490,"visible":true,"origin":"","legend":"\u003cp\u003eToughening mechanism of Sep-HEC. (A, B) SEM images of the tensile-fractured surface of Sep-HEC-M2/P2 at different magnification. (C, D, E) SEM images of the side view for Sep-HEC-M2/P2 at 0% strain, at 10% strain and fractured (about 40% strain).\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/c02698166f6b717d22c4f6ae.jpg"},{"id":89375297,"identity":"0acf92ce-62de-49fd-965a-5f85110805f5","added_by":"auto","created_at":"2025-08-19 10:54:17","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":140572,"visible":true,"origin":"","legend":"\u003cp\u003e(A) The UV-Vis transmittance spectra of casted HEC and Sep-HECs with various crosslinker content with a thickness of 0.3 mm. The tanδ-T curves (B) and weight-T curves (C) of Sep-HEC with various crosslinker contents. (D) The water contact angles of casted HEC and various Sep-HECs. (E) The stress-strain curves of casted HEC and various Sep-HECs after being placed in an oven for 48h at 60 RH% and 25 \u003csup\u003eo\u003c/sup\u003eC. (F) The stress-strain curves of Sep-HEC-M4/P4 after being soaked in different HCI solutions for 15 days and dried. The photos (G) and stress-strain curves (H) of Sep-HEC-M4/P4 after being soaked in various organic solvent and dried.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/bcde3616d498a2b0519dca38.jpg"},{"id":89406092,"identity":"b91ce1a0-c1e3-46d4-a236-7a99b507dbf7","added_by":"auto","created_at":"2025-08-19 15:14:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1267141,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/7adb69cb-ee88-4440-a11d-f38eefae2de3.pdf"},{"id":89375298,"identity":"ccc847d7-b80e-40fe-96fc-207b4235bb27","added_by":"auto","created_at":"2025-08-19 10:54:17","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1495016,"visible":true,"origin":"","legend":"Supporting Information","description":"","filename":"Supportinginformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/6871918440b6d29ac560fb16.docx"},{"id":89404766,"identity":"6053c9f3-8a3e-439b-96c8-0dda66d330bd","added_by":"auto","created_at":"2025-08-19 14:58:17","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":414451,"visible":true,"origin":"","legend":"","description":"","filename":"Graphicalabstract.docx","url":"https://assets-eu.researchsquare.com/files/rs-7148129/v1/bc419a5a96e01932b0cb5773.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Massively Preparable, Super-tough and Ultra-strong Cellulose-based Bioplastics Enabled by Microphase Separation","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePlastics have been one of the cornerstones of human civilization due to its indispensability in industry and daily life. To date, over 8\u0026nbsp;billion tons of plastics have been produced globally.\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e However, the wide use of plastics has seriously exacerbated the petroleum depletion and environmental pollution since most plastics are derived from non-renewable petroleum resources and hard to degrade. Under this background, bio-based plastics with good sustainability have attracted extensive attention from both the academia and industry in recent years. \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e Although bio-based polyesters represented by polylactic acid (PLA), polybutylene succinate (PBS) and polyhydroxyalkanoate (PHA) have received increasing attention, they cannot meet the actual demands due to the low production and inadequate properties. \u003csup\u003e[\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e Besides, starch-based plastics are sustainable plastics with high availability, high production and low cost, but their practical applications are severely limited by problems such as poor mechanical properties, high sensitivity to humidity and competition with humans for food sources. \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e Therefore, developing bio-based plastics with endless non-food sources and competitive properties are urgently pursued.\u003c/p\u003e\u003cp\u003eCellulose is the most abundant biopolymer on the earth with merits of endless non-food sources, high modulus, high strength and biodegradability, suggesting that it is an ideal alternative to replace petroleum-based plastics. \u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e However, due to the rigid backbone, the highly ordered structure and the high-density hydrogen bonding (H-bond), native celluloses show poor solubility in common solvents and poor thermoplastic processability, leading to the poor processability. \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e With the aid of special solvents (such as NaOH/urea, LiOH/urea and ionic liquids), native cellulose can be dissolved and molded by casting. \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e Nevertheless, these regenerated celluloses are very brittle due to the lack of chain-segment movability, leading to very limited practical applications. \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e Grafting aliphatic side chains onto cellulose can consume hydroxyl groups, weaken intermolecular H-bond and increase intermolecular distance, enabling the improved chain-segment movability, processability and toughness of cellulose derivatives. \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e However, the rigid backbone still makes it difficult for cellulose derivatives to be directly melt-blended or exhibit high toughness, unless a suitable plasticizer is introduced. \u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e In this case, plasticizers will significantly sacrifice the attractive high strength and high modulus of celluloses and result in the high sensitivity to moisture. \u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e Although cellulose nanopapers prepared by filtrating cellulose nanofibers\u0026rsquo; aqueous dispersion \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e and cellulose-based composites with \"brick-mortar\" structure \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e can show great tensile strength (above 200 MPa), they still suffer from poor toughness and low processing efficiency. Therefore, preparing strong and tough cellulose-based plastics via a large-scale method is still challenging.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn this work, a microphase separation strategy is proposed to prepare super-tough and ultra-strong cellulose-based plastic via a large-scale manner. Via soaking crosslinked hydroxyethyl cellulose (HEC) containing dimethyl sulfoxide (DMSO) into water, a unique water-mediated microphase separation occurs, enabling the formation of plentiful small-sized hydrophobic microphases (100\u0026thinsp;~\u0026thinsp;300 nm) into rigid HEC continuous phase. These microphases can serve as multifunctional phases to toughen HEC, improve the water resistance, shield ultraviolet light with short-wavelength and let through visible light with long wavelength. Consequently, the microphase-separated HEC (Sep-HEC) shows charming mechanical properties (a tensile strength of 147.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 MPa and a toughness of 30.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 MJ/m\u003csup\u003e3\u003c/sup\u003e), excellent optical properties (combined UV-shielding and transparency), good solvent resistance and excellent heat resistance. Moreover, the microphase separation is realized by thermoplastic processing and water-soaking process, highlighting the potential of large-scale preparation. The unprecedented combining of large-scale preparation and excellent comprehensive properties will promote the substitution of petroleum-based plastics by sustainable cellulosic plastics with endless sources.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003ePreparation and Characterization of the Sep-HEC\u003c/h2\u003e\u003cp\u003eThe preparation process of Sep-HEC consists of two steps, namely preparing crosslinked HEC with DMSO and inducing microphase separation of the crosslinked HEC by water. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, acrylated HEC (A-HEC) is firstly prepared by grafting methacryloyloxyethyl isocyanate (MOI) onto DMSO-plasticized HEC based on nucleophilic addition reaction between hydroxyl group and isocyanate. Subsequently, the A-HEC was crosslinked by pentaerythritol tetra(3-mercaptopropionate) (PETMP) based on thia-Michael reaction between thiol and acrylate to generate a crosslinked HEC (C-HEC) containing DMSO. \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e Then the C-HEC containing DMSO is immersed in water to leach out DMSO, during which the C-HEC undergoes microphase separation due to the aggregation of adjacent hydrophobic crosslinked structures and the self-assembling of HEC chains with dense H-bond, generating a Sep-HEC with water. After drying, the Sep-HEC is obtained. Samples with fixed DMSO content (equal to the HEC weight) and variable crosslinker contents are nominated as \u0026lsquo;Sep-HEC-Mx/Py\u0026rsquo;, where Mx represents the molar percentage (mol%) of MOI to the hydroxyl groups in HEC while Py represents the mol% of thiol in PETMP to the hydroxyl groups in HEC. Samples with fixed crosslinker content (M2 and P2) and variable DMSO contents are nominated as \u0026lsquo;Sep-HEC-DMSOz\u0026rsquo;, where z represents the weight percentage (wt%) of DMSO to HEC. Sep-HEC-DMSO300, a Sep-HEC with a high HEC content of 94 wt%, is selected as a represent. Photos shows its high transparency and excellent flexibility (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). The stress-strain curve displays the ultra-high tensile strength (σ) of 147.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 MPa and the high elongation at break (ε) of 30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8% (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC), enabling a remarkable toughness (as indicated by the work to failure of per unit volume) of 30.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 MJ/m\u003csup\u003e3\u003c/sup\u003e. Besides, Sep-HEC-DMSO300 also possesses excellent ultraviolet shielding effect (about 90%, \u003cb\u003eFigure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e), high decomposing temperature (T\u003csub\u003ed,max\u003c/sub\u003e=377 \u003csup\u003eo\u003c/sup\u003eC, \u003cb\u003eFigure S2\u003c/b\u003e) and high T\u003csub\u003eg\u003c/sub\u003e (167.9 \u003csup\u003eo\u003c/sup\u003eC, \u003cb\u003eFigure S3\u003c/b\u003e). Compared with some representative commercial plastics, such as general plastic polystyrene (PS), engineering plastic polycarbonate (PC) and bio-based plastic poly(lactic acid) (PLA), the Sep-HEC-DMSO300 shows great superiority in terms of mechanical properties, thermal properties and UV-shielding properties (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD), suggesting the great potential to replace traditional plastics.\u003c/p\u003e\u003cp\u003eThe successful graft of MOI onto HEC is verified by FTIR spectra, where characteristic peaks of MOI, including C\u0026thinsp;=\u0026thinsp;O (1720 cm⁻\u0026sup1;), C\u0026thinsp;=\u0026thinsp;C (1634 cm⁻\u0026sup1;) and C-O-C (1156 cm⁻\u0026sup1;), can be clearly observed in A-HEC (\u003cb\u003eFigure S4\u003c/b\u003e). In \u003cb\u003eFigure S5\u003c/b\u003e, characteristic peak of thiol (2570 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in PETMP and C\u0026thinsp;=\u0026thinsp;C (1634 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in A-HEC disappear in the C-HEC while characteristic peak of C\u0026thinsp;=\u0026thinsp;O (1728 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in PETMP is observed in the C-HEC, demonstrating the occurrence of thia-Michael reaction convincingly. Besides, the insolubility of C-HEC in DMSO (\u003cb\u003eFigure S6\u003c/b\u003e) and the high gel content (\u0026gt;\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e78%) of various C-HECs (\u003cb\u003eFigure S7 and S8\u003c/b\u003e) verify the crosslinked structure of C-HEC. Interestingly, increasing the crosslinker content doesn\u0026rsquo;t increase the gel content of C-HEC obviously (\u003cb\u003eFigure S7\u003c/b\u003e) while increasing the DMSO content does (\u003cb\u003eFigure S8\u003c/b\u003e). This is due to the macroscopically uniform but microscopically non-uniform dispersion of the crosslinkers, which is caused by the limited content of DMSO and the high viscosity of the plasticized HEC. Thus, increasing DMSO content can effectively reduce the viscosity of plasticized HEC and optimize the dispersion of crosslinkers, thereby increasing the gel content. This result also indicates the non-uniformity of the crosslinked structure at microscopic level. Notably, DMSO can be both a highly efficient plasticizer for HEC and a solvent for MOI and PETMP while the employed reactions can be realized efficiently under mild conditions. Therefore, the plasticization, modification and crosslinking can be achieved by thermoplastic processing which is easy to scale.\u003c/p\u003e\u003cp\u003eThe C-HEC containing DMSO possesses high chain-segment movability and thermodynamically incompatible structures (the crosslinking point and the HEC chain-segment away from crosslinking point), enabling the water-mediated microphase separation where thermodynamically compatible structures aggregate and incompatible structures separate. \u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e The high chain-segment movability of C-HEC containing DMSO, which is enabled by the plasticizing effect of DMSO, is evidenced by the low T\u003csub\u003eg\u003c/sub\u003e (\u003cb\u003eFigure S9\u003c/b\u003e) and the low young\u0026rsquo;s modulus (550\u0026thinsp;\u0026plusmn;\u0026thinsp;32 kPa) (\u003cb\u003eFigure S10\u003c/b\u003e). To reveal the water-mediated microphase separation, the Sep-HEC-M2/P2 with water was freeze-dried (Sep-HEC-M2/P2-FD) and the condensed-state structures was investigated. SEM image of Sep-HEC-M2/P2-FD reveals the interconnected skeleton and lots of large pores (dozens of microns), where the skeleton contains plentiful small microphases (100\u0026thinsp;~\u0026thinsp;200 nm) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). These large pores should relate to water-rich regions, and should originate from the sparsely crosslinked domains with high hydrophilicity and less covalent linkages. The skeleton should originate from the highly crosslinked regions with improved hydrophobicity and more covalent linkages. These microphases in skeleton should root from the aggregation of adjacent hydrophobic crosslinked structures under water stimulation. For Sep-HEC-M2/P2 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB), plentiful small microphases (100\u0026thinsp;~\u0026thinsp;300 nm) are observed while no large pores are observed, suggesting the remaining of the microphase and the densification of HEC chains during the thermal drying. In the tanδ-T relationship curves (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC), Sep-HEC-M2/P2-FD exhibits two glass transitions, namely a main peak around 161\u0026deg;C and a shoulder peak around 100\u0026deg;C, confirming the two-phase structure. The main peak should correspond to the continuous phase in the skeleton while the shoulder peak should relate to the microphase in the skeleton. The lower T\u003csub\u003eg\u003c/sub\u003e of microphase is due to the crosslinked structures which can consume hydroxyl groups and increase the interchain distance. For Sep-HEC-M2/P2, two glass transitions confirms the remaining of the microphase. Besides, the main glass transition shows a decreased intensity while the glass transition relating to microphase is enhanced and blurred when compared with Sep-HEC-M2/P2-FD, suggesting the increased interface layer which should originate from the densification of HEC chains around microphases during the thermal drying. Moreover, AFM micrographs further provide direct evidences for the microphase separation structure of Sep-HEC-M2/P2. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eD and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eE, a sea-island microphase separation structure is clearly observed, where the microphase shows a small size of 100\u0026thinsp;~\u0026thinsp;200 nm and a lower modulus than that of the continuous phase.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMechanical Properties of Sep-HECs.\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe mechanical properties of all samples are provided in \u003cb\u003eTable \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e and\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA displays the stress-strain curves of casted HEC and Sep-HECs with various crosslinker contents. Both the σ and the ε of Sep-HECs are much higher than that of the casted HEC, demonstrating the great superiority of Sep-HECs in mechanical properties. For example, the casted HEC exhibits a σ of 19.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.1 MPa and an ε of 9.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5% while Sep-HEC with a few crosslinkers (Sep-HEC-M2/P2) shows a σ of 100.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.7 MPa and an ε of 39.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3%. Besides, increasing the crosslinker content can increase the ε but decrease the σ of Sep-HECs, notifying that the crosslinked structure mainly contributes to the high extensibility. Addition to the crosslinker content, DMSO content can also powerfully affect the\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003emechanical properties of Sep-HECs. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB, compared to Sep-HEC-DMSO100, Sep-HEC-DMSO300 shows a greatly improved σ of 147.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 MPa and a slightly decreased ε of 30.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8%, enabling a super toughness of 30.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 MJ/m\u003csup\u003e3\u003c/sup\u003e. The excellent mechanical properties enable a small specimen (0.09 g) of Sep-HEC-M2/P2 to lift a weight of 6.0 kg which is more than 60000 times of the specimen\u0026rsquo;s weight (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC). Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD compares the σ and toughness of the as-fabricated Sep-HECs and some representative cellulose-based plastics. Although regenerated cellulose films exhibit high σ above 100 MPa, the low ε leads to the poor toughness below 6 MJ/m\u003csup\u003e3\u003c/sup\u003e. \u003csup\u003e[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e Cellulose nanopapers prepared from cellulose nanofibers can show ultra-high σ, and subtly designed microstructure structure enables a toughness above 10 MJ/m\u003csup\u003e3\u003c/sup\u003e. \u003csup\u003e[\u003cspan additionalcitationids=\"CR26 CR27\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e However, the ε is still very limited, resulting in a toughness less than 13 MJ/m\u003csup\u003e3\u003c/sup\u003e. Chemical modification and incorporating plasticizers can effectively improve the ε of cellulose-based plastics, but the σ is sharply decreased and the ε is generally less than 80%, resulting in a limited toughness. \u003csup\u003e[\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e As a stark contrast, the as-fabricated\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eSep-HECs possess both high σ and high toughness. Particularly, Sep-HEC-DMSO300 shows a high σ of 147.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 MPa and a super toughness of 30.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 MJ/m\u003csup\u003e3\u003c/sup\u003e, which is unprecedented for cellulose-based plastics. Moreover, the σ of Sep-HEC-DMSO300 is much greater than most commercially available plastics while the toughness is superior to or comparable with them, highlighting the great potential to replace petroleum-based plastic (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD).\u003c/p\u003e\u003cp\u003eTo understand the mechanism for the excellent mechanical properties of Sep-HECs, the tensile-fractured surface of Sep-HEC-M2/P2 is firstly observed by SEM. In Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, Sep-HEC-M2/P2 show a highly rough surface with obvious deformation of partial matrices, indicating a ductile fracture rooting from the motion of partial chain-segments. Meanwhile, some large-sized cracks are observed on the surface, which should be responsible for the fracture of the sample. Then the side view of Sep-HEC-M2/P2 with various strain are recorded. With 10% strain, plentiful small grooves perpendicular to the external force are observed around the microphase (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eD), suggesting that the microphase can act as stress concentration points to induce small microcracks. These microcracks should originate from the forced movement of partial chain-segments, and can arrest and dissipate energy. When the strain reaches the break strain (about 40%), the grooves become more obvious and some grooves are deflected (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eE), suggesting the development of the microcracks and the rearrangement of partial HEC chains. The rearrangement of partial HEC chains will continuously dissipate energy, enabling the development of microcracks and inhibiting the quick transformation of microcracks into macrocracks. Meanwhile, some cracks parallel to the external force are also observed in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eE, which should originate from the development of microvoids and be responsible for the fracture of the sample. Notably, although both microphases and microvoids can act as stress concentration points to induce microcracks, they show quite different effects. For microphases with small size and high quantity, they induce plentiful small-sized microcracks which can dissipate energy, promote the rearrangement of HEC chains and develop continuously during deformation, playing a toughening role. For microvoids with large size and small quantity (as revealed by Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB), they induce a few large-sized microcracks which will develop into cracks and fracture the sample. In addition, although the contribution of a single microcrack to ε is very limited, plentiful microcracks enable a significantly improved ε. Therefore, the super toughness mainly roots from the plentiful microcracks induced by microphases, and the high content of microphases is vital for the high extensibility. Furthermore, the high strength of Sep-HEC-M2/P2 should originate from the glassy state of all chain-segments and the high rigidity of continuous phase, which are evidenced by the DMA results (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC and S11).\u003c/p\u003e\u003cp\u003eBased on the above mechanism, we can well explain the mechanical behaviors of different Sep-HECs. Plentiful microcracks induced by numerous microphases enable the large ε (\u0026gt;30%) of all Sep-HECs. With a fixed DMSO content, increasing crosslinker content can increase the microphase content, leading to the improved ε and decreased σ. When the crosslinker content is fixed, increasing DMSO content can promote the moving and assembling of HEC chain-segments into a rigid skeleton, resulting in the reduced microphase content, decreased ε and increased σ.\u003c/p\u003e\u003cp\u003e\u003cb\u003eOptical, thermal and solvent-resistant properties of Sep-HECs.\u003c/b\u003e\u003c/p\u003e\u003cp\u003eSep-HECs show excellent UV-shielding effect while maintaining a good transparency. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA, casted HEC shows negligible UV-shielding effect. In sharp contrast, Sep-HECs exhibit excellent UV-shielding effect, and the effect is enhanced with the increment of crosslinker content. For instance, Sep-HEC-M2/P2 can effectively shield UV below 300 nm, while Sep-HEC-M6/P6 can shield all UV below 400 nm. Meanwhile, all Sep-HECs show good transparency as their transmittances at 550 nm are higher than 70%. The combined UV-shielding and high transparency should be attributed to the small-sized microphases which can strongly scatter UV light with short-wavelength and weakly scatter visible light with long-wavelength. Besides, Sep-HECs show high T\u003csub\u003eg\u003c/sub\u003es with the value above 160 \u003csup\u003eo\u003c/sup\u003eC, suggesting the excellent dimensional stability at high temperature (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB). Sep-HECs also possess high decomposition temperature (T\u003csub\u003ed\u003c/sub\u003e) with the starting T\u003csub\u003ed\u003c/sub\u003e above 310 \u003csup\u003eo\u003c/sup\u003eC and the fastest T\u003csub\u003ed\u003c/sub\u003e above 370 \u003csup\u003eo\u003c/sup\u003eC (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eC and S12), indicating the good thermostability.\u003c/p\u003e\u003cp\u003eSep-HECs show good solvent resistance as well. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eD, casted HEC shows a low\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003ewater contact angle of 23\u003csup\u003eo\u003c/sup\u003e while various Sep-HECs display high water contact angles above 80\u003csup\u003eo\u003c/sup\u003e, suggesting the obviously improved hydrophobicity. Although casted HEC and Sep-HECs show weakened σ after being placed in an oven for 48h at 60 RH% and 25 \u003csup\u003eo\u003c/sup\u003eC due to the adsorption of water, Sep-HEC-M2/P2 possesses a high σ of 50.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8 MPa and a high ε of 76.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2% (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eE), suggesting the applicability in high-humidity environments. After being soaked in different HCI solutions for 15 days and dried, Sep-HEC-M4/P4, a Sep-HEC with relatively high crosslinker content, shows similar stress-strain curves before and after soaking (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eF), highlighting the excellent resistance to acid environment of Sep-HECs. Moreover, Sep-HEC-M4/P4 can well maintain its original shape after being soaked in common organic solvents, such as ethyl acetate, toluene and ether (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eG). After being dried, these soaked Sep-HEC-M4/P4s exhibit mechanical properties comparable to the unsoaked sample (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eH), notifying the excellent resistance to organic solvents.\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn summary, we successfully develop a cellulose-based plastic with super toughness, ultra-high strength and excellent comprehensive properties based on the water-mediated microphase separation strategy. Based on the unique toughening mechanism of small microphases (100\u0026thinsp;~\u0026thinsp;300 nm) via inducing plentiful small microcracks, the rigid Sep-HEC-DMSO300 shows both a charming tensile strength of 147.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 MPa and a super toughness of 30.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 MJ/m\u003csup\u003e3\u003c/sup\u003e, providing inspiration for the design of stiff and tough polymers. Besides, the microphase can strongly scatter UV light and weakly scatter visible light, enabling the excellent UV-shielding effect and good transparency of Sep-HEC. Moreover, the combined crosslinking structure, hydrophobic microphase and hydrophilic continuous phase impart Sep-HEC with good resistance to both water and organic solvent. The rigid backbone of HEC and decreased content of hydroxyl groups enable the high T\u003csub\u003eg\u003c/sub\u003e (\u0026ge;\u0026thinsp;160 \u003csup\u003eo\u003c/sup\u003eC) and high T\u003csub\u003ed\u003c/sub\u003e (T\u003csub\u003ed, max\u003c/sub\u003e\u0026ge;370 \u003csup\u003eo\u003c/sup\u003eC) of Sep-HEC. Furthermore, the microphase separation is achieved by thermoplastic processing and water-soaking process, highlighting the potential of large-scale preparation for the high-performance bioplastic. The combined large-scale preparation and excellent comprehensive properties are unprecedented for cellulose-based plastics, and will promote the substitution of petroleum-based plastics by cellulosic plastics with endless sources.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eMaterials\u003c/strong\u003e. Hydroxyethyl cellulose (HEC) with a molar degree of substitution of 2.09 was purchased from Shandong YouSuo Chemical Technology Co., Ltd. Methacryloyloxyethyl isocyanate (MOI) was purchased from Shanghai Titan Technology Co., Ltd. Pentaerythritol tetra(3-mercaptopropionate) (PETMP) and dimethyl sulfoxide (DMSO) were purchased from Shanghai McLean Biochemical Technology Co., Ltd.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreparation of crosslinked HEC containing DMSO.\u003c/strong\u003e Take crosslinked HEC-M2/P2 as an example, 25.0 g powdery HEC (0.3 mol hydroxyl group) and 15 g DMSO (60 wt% of HEC) were added into an internal mixer at 70\u0026deg;C and blended for 8 min to prepare plasticized HEC. Subsequently, 0.9 g MOI (6 mmol) in 5 g DMSO (20 wt% of HEC) was dropped into the internal mixer and reacted for 20 min at 70 \u003csup\u003eo\u003c/sup\u003eC under continuous blending. Then, 0.7 g PETMP (6 mmol thiol groups) in 5 g DMSO (20 wt% of HEC) was dropped into the internal mixer and reacted for 20 min at 70 \u003csup\u003eo\u003c/sup\u003eC under continuous blending. Then the blend was hot-pressed at 140 \u003csup\u003eo\u003c/sup\u003eC for 20 min to obtain the crosslinked HEC containing DMSO in the form of sheet. To regulate the crosslinking structure, the contents of MOI and thiol groups were designed as 2 mol%, 4 mol% and 6 mol% of hydroxyl group in HEC, with a fixed DMSO content of 100 wt% of HEC. Furthermore, the DMSO content was designed as 100 wt%, 200 wt% and 300 wt% of HEC to manipulate the movability of HEC chains, with a fixed MOI and thiol groups of 2 mol% of hydroxyl group in HEC.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreparation of Sep-HEC.\u003c/strong\u003e The crosslinked HEC sheet containing DMSO was soaked into deionized water for 30 min and the soaking was repeated for 3 times to fully leach out DMSO and induce microphase separation. Then the sample after soaking was placed in a fume hood for 6 hours and dried in a vacuum oven at 60\u0026deg;C until constant weight to obtain the microphase-separated HEC-based plastic (Sep-HEC).\u003c/p\u003e\n\u003cp\u003eSince HEC can solve in water, HEC film, a contrast sample, was prepared by casting HEC aqueous solution with a concentration of 1 w/v%.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacterization.\u003c/strong\u003e The FTIR spectra were performed on a Nicolet iS50 FTIR spectrometer over the range of 400\u0026ndash;4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The TGA curves were recorded by a TGA2 thermogravimetric analyzer in an N\u003csub\u003e2\u003c/sub\u003e atmosphere with a temperature range of 25\u0026ndash;700 \u003csup\u003eo\u003c/sup\u003eC. The UV-Vis spectra were recorded by a TU-1950 UV-visible spectrophotometer over the range of 200\u0026ndash;800 nm. The stress-strain curve was performed on an Al-7000-SU1 test tensile machine at room temperature with a tensile rate of 1 mm/min. The toughness, which is reflected by the work to failure of per unit volume of the sample, was calculated by integrating the stress-strain curve. At least 5 specimens were measured for each sample to ensure the accuracy and reproducibility of the data. SEM images were recorded by a HITACHI S-4800 scanning electron microscopy with an accelerated voltage of 1 kV. AFM images were recorded by a MuLtimode 8 atomic force microscope. The specimens for AFM measurement were prepared by freezing slice. The contact angle was recorded by a Theta Flow video-optical contact angle meter. DMA was performed on a DMA850 dynamic mechanical analyzer with a temperature range of 30\u0026ndash;200 \u003csup\u003eo\u003c/sup\u003eC and a ramp rate of 3 \u003csup\u003eo\u003c/sup\u003eC/min. The gel content was measured by following the steps. The crosslinked HEC containing DMSO was completely dried firstly. Then specific content of sample (about 0.5 g) was weighed (m\u003csub\u003e0\u003c/sub\u003e) and soaked in sufficient DMSO for 72 h under continuous slight oscillation. The DMSO was exchanged every 24 h to ensure the completely dissolving out of soluble portions. Then the residual gel was dried and weighed (m\u003csub\u003e1\u003c/sub\u003e). The gel content was calculated by Eq.\u0026nbsp;(\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e):\u003c/p\u003e\n\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e$$\\:\\text{g}\\text{e}\\text{l}\\:\\text{c}\\text{o}\\text{n}\\text{t}\\text{e}\\text{n}\\text{t}\\:\\left(\\text{%}\\right)={m}_{1}/{m}_{0}\\:\\times\\:100$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eConflict of Interest\u003c/h2\u003e\u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eAcknowledgment\u003c/h2\u003e\u003cp\u003eThis work was supported by National Natural Science Foundation of China (52273089, 52303127).\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data required to assess the conclusions of this paper are included within the paper and the Supplementary Information. The data are available from the corresponding authors upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRan JR, Talebian-Kiakalaieh A, Zhang S, Hashem EM, Guo MJ, Qiao SZ (2024) Chem Sci 15:1611\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCywar RM, Rorrer NA, Hoyt CB, Beckham GT, Chen EYX (2022) Nat Rev Mater 7:83\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi XR, Lin Y, Liu ML, Meng LP, Li CF (2023) J Appl Polym Sci 140\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBarletta M, Aversa C, Ayyoob M, Gisario A, Hamad K, Mehrpouya M, Vahabi H (2022) Prog Polym Sci 132\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSharma V, Sehgal R, Gupta R (2021) Polymer 212\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSiqueira LD, Arias CIL, Maniglia BC, Tadini CC (2021) Curr Opin Food Sci 38:122\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi T, Chen CJ, Brozena AH, Zhu JY, Xu LX, Driemeier C, Dai JQ, Rojas OJ, Isogai A, W\u0026aring;gberg L, Hu LB (2021) Nature 590:47\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRay U, Zhu SZ, Pang ZQ, Li T (2021) Adv Mater 33\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZugenmaier P (2021) \u003cem\u003eCarbohyd Polym\u003c/em\u003e 254\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTu H, Zhu MX, Duan B, Zhang LN (2021) Adv Mater 33\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSu H, Wang BJ, Sun ZQ, Wang SL, Feng XL, Mao ZP, Sui XF (2022) Carbohyd Polym 277\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCheng WK, Zhu Y, Jiang GY, Cao KY, Zeng SQ, Chen WS, Zhao DW, Yu HP (2023) Prog Mater Sci 138\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi XK, Qiu XY, Yang X, Zhou P, Guo QQ, Zhang XX (2024) Adv Mater 36\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBonifacio A, Bonetti L, Piantanida E, De Nardo L (2023) Eur Polym J 197\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu W, Liu K, Du HS, Zheng T, Zhang N, Xu T, Pang B, Zhang XY, Si CL, Zhang K (2022) Nano-Micro Lett 14\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen F, Xiang WC, Sawada D, Bai L, Hummel M, Sixta H, Budtova T (2020) ACS Nano 14:11150\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGuan QF, Yang HB, Han ZM, Zhou LC, Zhu YB, Ling ZC, Jiang HB, Wang PF, Ma T, Wu HA, Yu SH (2020) Sci Adv 6\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSun H, Ji T, Ren ZC, Bi HJ, Xu M, Huang ZH, Cai LP (2022) Ind Crop Prod 180\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi CY, Zhang XH, Chen H, Wang HT, Huang J, Li T, Wang SB, Dong WF (2025) Int J Biol Macromol 295\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang ZW, Qiu WL, Zhang Q (2024) Prog Polym Sci 154\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHu JY, Hou LX, Zhu A, Qiu HN, Zhang ZR, Du C, Cui KP, Zheng Q, Wu ZL (2024) Macromolecules 57:11007\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu SL, Zhang LN, Sun YX, Lin Y, Zhang XZ, Nishiyama Y (2009) Macromol Biosci 9:29\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang TP, Zhang XF, Chen YW, Duan YX, Zhang JM (2018) Acs Sustain Chem Eng 6:1271\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePang JH, Wu M, Zhang QH, Tan X, Xu F, Zhang XM, Sun RC (2015) Carbohyd Polym 121:71\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSun WB, Han ZM, Yue X, Zhang HY, Yang KP, Liu ZX, Li DH, Zhao YX, Ling ZC, Yang HB, Guan QF, Yu SH (2023) Adv Mater 35\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHenriksson M, Berglund LA, Isaksson P, Lindstr\u0026ouml;m T, Nishino T (2008) Biomacromolecules 9:1579\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMao R, Meng N, Tu W, Peijs T (2017) \u003cem\u003eCellulose\u003c/em\u003e 24, 4627\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang DJ, Fang ZQ, Hu SQ, Qiu XQ (2024) Carbohyd Polym 346\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYang ZY, Wang WJ, Shao ZQ, Zhu HD, Li YH, Wang FJ (2013) Cellulose 20:159\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLu ZQ, Huang JZ, E SF, Li JY, Si LM, Yao C, Jia FF, Zhang MY (2020) Carbohyd Polym 250\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWang B, Chen JY, Peng HM, Gai JG, Kang J, Cao Y (2016) J Macromol Sci B 55:894\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBenitez JJ, Florido-Moreno P, Porras-V\u0026aacute;zquez JM, Tedeschi G, Athanassiou A, Heredia-Guerrero JA (2024) S. Guzman-Puyol. Int J Biol Macromol 273\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7148129/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7148129/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe growing environmental concern over petroleum-based plastics have promoted the exploration of sustainable bioplastics with competitive properties. Cellulose is an ideal sustainable alternative with endless sources and biodegradability, but poor processability and poor toughness severely restrict their practical applications. Herein, a microphase separation strategy is proposed to massively prepare super-tough and ultra-strong cellulosic plastics. The microphase separation is realized by thermoplastic processing and water-soaking process, highlighting the potential of large-scale preparation. The combined microphases (100\u0026thinsp;~\u0026thinsp;300 nm) and rigid continuous phase enable a tensile strength of 147.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 MPa and a toughness of 30.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1 MJ/m\u003csup\u003e3\u003c/sup\u003e, where numerous microphases play a unique toughening role via forcing the movement of rigid chain-segments. Besides, the microphase-separated cellulosic plastics possess excellent UV-shielding effect, good transparency, high glass transition temperature, high decomposition temperature and good solvent resistance, stressing the excellent comprehensive properties and wide applicability. The combined large-scale preparation and excellent comprehensive properties are unprecedented for cellulosic plastics. This work provides a novel yet facile microphase separation strategy to prepare high-performance cellulosic plastics, and will promote the substitution of petroleum-based plastics by sustainable cellulosic plastics with endless sources.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e","manuscriptTitle":"Massively Preparable, Super-tough and Ultra-strong Cellulose-based Bioplastics Enabled by Microphase Separation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-19 10:54:12","doi":"10.21203/rs.3.rs-7148129/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"2e12d4e3-b4ef-4545-82d3-555c88825488","owner":[],"postedDate":"August 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":52806232,"name":"Physical sciences/Materials science/Structural materials/Mechanical properties"},{"id":52806233,"name":"Physical sciences/Materials science/Techniques and instrumentation/Design, synthesis and processing"}],"tags":[],"updatedAt":"2025-08-19T10:54:12+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-19 10:54:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7148129","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7148129","identity":"rs-7148129","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}