Qi Zhou

Nonisocyanate polyurethanes are sustainable alternatives to conventional polyurethanes but often exhibit limited mechanical performance. Here, poly(hydroxyurethane) (PHU)–epoxy hybrid networks were prepared to tune matrix stiffness through covalent cross-linking and reinforced with wood- and tunicate-derived cellulose nanocrystals (CNCs). Increasing epoxy content enhanced Young’s modulus and tensile strength while reducing strain at break. In contrast, incorporation of CNCs into an intermediate PHU–epoxy matrix produced substantial mechanical enhancement at low loadings. Tunicate-derived CNCs, characterized by higher aspect ratios, provided greater reinforcement than wood-derived CNCs and achieved a maximum toughness of ∼27 MJ m–3 at 2 wt %, exceeding both wood-derived CNC nanocomposites (≤17 MJ m–3) and neat PHU–epoxy hybrids (≤16.5 MJ m–3). Scanning electron microscopy confirmed homogeneous CNC dispersion, while Fourier transform infrared spectroscopy indicated extensive hydrogen-bonding interactions. These results demonstrate that epoxy hybridization and high-aspect-ratio CNC reinforcement provide complementary routes to enhance the mechanical performance of biobased PHU materials.

Replacing petrochemical plastics with sustainable materials requires strategies that combine high mechanical performance with low environmental impact. Here, we report an ultrastrong and tough cellulose paper created by integrating multiscale cellulose materials to overcome the weak fiber-to-fiber adhesion found in conventional paper. Bacterial cellulose microgels fill microscale voids between pulp fibers, while bacterial cellulose nanofibers reinforce nanoscale gaps, forming densely bonded interfaces through capillary-driven assembly during dehydration. This hybrid structure significantly enhances interfacial interactions and hydrogen bonding, producing cellulose paper with isotropic tensile strength of 811 MPa and robust wet-state performance. The process is highly energy-efficient due to rapid dewatering, consuming far less energy than nanocellulose-paper manufacturing. The resulting material also exhibits strong adhesion to hydrophilic substrates, expanding its application potential. By bridging the performance gap between natural cellulose fibers and traditional paper, this work provides a biodegradable, energy-efficient alternative to plastics for sustainable structural and packaging applications.

Polyurethanes are widely used in adhesive applications, but their conventional synthesis relies on hazardous isocyanates and often solvent-based formulations. In this work, waterborne polyhydroxyurethanes (PHUs) were synthesized from 1,6-hexanediol bis(cyclic carbonate) and bio-based Priamine 1075 via catalyst-free suspension polymerization in water. Pristine cellulose nanocrystals (CNCs) acted as the sole stabilizers, eliminating the need for petroleum-derived surfactants while simultaneously serving as reinforcing nanofillers. Stable monomer-in-water emulsions were obtained with CNC loadings up to 200 mg mL -1 per monomer, corresponding to ~17 wt % CNCs in the final dried nanocomposites. In the latex state, CNCs were located at the particle surfaces, ensuring colloidal stability, while in the dried PHU/CNC nanocomposites they were uniformly distributed throughout the matrix, yielding adhesives with markedly enhanced performance. The nanocomposites exhibited up to 680% and 340% increases in probe tack adhesion strength and lap-shear strength, respectively, compared with surfactant Tween 80stabilized waterborne PHUs, reaching performance levels comparable to commercial pressuresensitive adhesives. These findings demonstrate that combining bio-based monomers with CNC stabilization offers a robust strategy for producing sustainable, high-performance PHU adhesives consistent with green chemistry principles.

Surface modification of cellulose nanocrystals (CNCs) offers a sustainable route to enhance their interfacial compatibility and functionality in CNCs‐stabilized polymer latexes. Here, CNCs were hydrophobically modified through covalent grafting of octylamine onto aldehyde‐functionalized CNCs produced by periodate oxidation. CNCs with different degrees of octylamine substitutions all remained colloidally stable in water but exhibited different surface hydrophobicity. When employed as stabilizers for waterborne polyhydroxyurethane (PHU) latexes, octylamine modified CNCs (oCNCs) significantly reduced droplet and latex diameters compared to pristine CNCs, demonstrating the critical role of surface hydrophobicity in Pickering stabilization. Among the modified samples, oCNCs with the lowest degree of modification provided the most effective reinforcement in PHU/oCNC nanocomposite adhesives, achieving a 60% increase in adhesion strength and a 54% increase in adhesion energy compared to pristine CNC‐stabilized PHU latexes with 9 wt.% CNCs. Increasing oCNCs loading to 17 wt.% further improved Tak adhesion strength to 1.0 MPa without sacrificing extensibility. The enhanced performance was attributed to optimized hydrophilic–hydrophobic balance and strong interfacial adhesion between oCNCs and the PHU matrix. This work establishes a simple and scalable chemical modification strategy for tailoring CNCs surface properties, enabling their dual role as stabilizers and reinforcements in high‐performance, waterborne, bio‐based polyurethane adhesives.

Polyurethanes are widely used in adhesive applications, but their conventional synthesis relies on hazardous isocyanates and often solvent-based formulations. In this work, waterborne polyhydroxyurethanes (PHUs) were synthesized from 1,6-hexanediol bis­(cyclic carbonate) and bio-based Priamine 1075 via catalyst-free suspension polymerization in water. Pristine cellulose nanocrystals (CNCs) acted as the sole stabilizers, eliminating the need for petroleum-derived surfactants while simultaneously serving as reinforcing nanofillers. Stable monomer-in-water emulsions were obtained with CNC loadings up to 200 mg mL^–1 per monomer, corresponding to ∼17 wt % CNCs in the final dried nanocomposites. In the latex state, CNCs were located at the particle surfaces, ensuring colloidal stability, while in the dried PHU/CNC nanocomposites they were uniformly distributed throughout the matrix, yielding adhesives with markedly enhanced performance. The nanocomposites exhibited up to 680% and 340% increases in probe tack adhesion strength and lap-shear strength, respectively, compared with surfactant Tween 80-stabilized waterborne PHUs, reaching performance levels comparable to commercial pressure-sensitive adhesives. These findings demonstrate that combining bio-based monomers with CNC stabilization offers a robust strategy for producing sustainable, high-performance PHU adhesives consistent with green chemistry principles.

This work pioneers CNC-stabilized waterborne non-isocyanate polyurethane latexes via Pickering emulsion polymerization, achieving surfactant-free, fluorescent and sustainable materials.

Incorporating biobased nanofillers including cellulose nanocrystals (CNCs) and chitin nanocrystals (ChNCs) into nonisocyanate polyurethane (NIPU) offers a multifunctional approach to improving mechanical and thermal properties while promoting sustainability and green chemistry. Nanocomposites of segmented thermoplastic polyhydroxyurethane (PHU) from vanillyl alcohol bis(cyclocarbonate) (VABC), poly(tetramethylene oxide) diamine (PTMODA), and bis(aminomethyl) norbornane (NORB) reinforced with a low amount of CNCs and partially deacetylated ChNCs were prepared and characterized. Fourier transform infrared spectroscopy, atomic force microscopy, and small-angle X-ray scattering revealed that partially deacetylated ChNCs were covalently grafted to the PHU through aminolysis of carbonate end groups in the hard segment, while CNCs were mixed with the PHU without interfacial covalent bonding. Consequently, the PHU/ChNC nanocomposites showed nanophase separation with smaller hard domains compared to neat PHU, while the PHU/CNC nanocomposites exhibited a phase-mixed system with broader interface regions. Dynamic mechanical analysis and tensile tests further revealed that the PHU/ChNC nanocomposites demonstrated a 49-fold increase in Young's modulus, a 20-fold increase in ultimate tensile strength, and a three-order-of-magnitude enhancement in storage modulus in the rubbery state compared to the PHU/CNC nanocomposites, highlighting the profound influence of interfacial covalent linkages in enhancing the thermal mechanical performance of segmented PHU.

The 3D micro- and nanostructure of wood has extensively been employed as a template for cost-effective and renewable electronic technologies. However, other electroactive components, in particular native lignin, have been overlooked due to the absence of an approach that allows access of the lignin through the cell wall. In this study, we introduce an approach that focuses on establishing conjugated-polymer-based electrical connections at various length scales within the wood structure, aiming to leverage the charge storage capacity of native lignin in wood-based energy storage electrodes. We demonstrate that poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) PEDOT/PSS, integrated within the cell wall lumen, can be interfaced with native lignin through the wood cell wall through in situ polymerization of a water-soluble S-EDOT monomer. This approach increases the capacitance of the conductive wood to 315 mF cm-2 at a scan rate of 5 mV s-1, which is seven and, respectively, two times higher compared to the capacitance of conductive wood made with the single components PEDOT/PSS or S-PEDOT. Moreover, we show that the capacitance is contributed by both the electroactive polymers and native lignin, with native lignin accounting for over 70% of the total charge storage capacity. We show that accessing native lignin through in situ creation of electrical interconnections within the wood structure offers a pathway toward sustainable, wood-based electrodes with improved charge-storage capacity for applications in electronics and energy storage.