High-strength thermo-moldable cellulose-based bioplastics for sustainable 3D structured materials

Hydrogen-bond substitution yields thermo-moldable cellulose-based bioplastics. • The bioplastic exhibits 120 MPa superior strength and high heat resistance (200 °C). • Water-assisted thermo-molding enables fabrication of complex 3D structures. • This material offers a promising sustainable alternative to petrochemical plastics. Scalable fabrication of native cellulose into 3D sustainable products is fundamentally challenged by its intrinsic dense hydrogen bonds and rigid backbone, which render conventional thermoplastic processing unfeasible. To address the inherent trade-off between processability and mechanical performance of cellulose-based materials, herein we adopted a supramolecular hydrogen-bond substitution strategy to construct a thermo-moldable bioplastic with tunable supramolecular hydrogen-bond network via intercalating flexible polyhydroxy PVA segments into the cellulose molecules to replace rigid cellulose-cellulose hydrogen bonds with cellulose-PVA hydrogen bonds. Epichlorohydrin (ECH) was introduced to covalently bridge cellulose and PVA chains, to prevent phase separation during dissolution and regeneration. After covalent bridging with cellulose, the glass transition temperature of PVA increased significantly from 66.5 °C to 80.1 °C, which was ascribed to the formation of thermally responsive cellulose-PVA hydrogen bonding networks that dissociated at temperatures above 132.1 °C. Benefiting from robust hydrogen bonds with reversible disruption and reformation, the cellulose-derived bioplastic can be fabricated into 3D structures via water-assisted thermo-molding. Notably, the material achieved an exceptional tensile strength of 120.0 MPa together with heat resistance up to 200 °C, outperforming a variety of common plastics. Furthermore, it exhibited an oxygen permeability coefficient of 1.01 × 10 −1  cm 3 ·cm / (m 2 ·h·0.1 MPa), accompanied by moderate water stability and oil resistance. This scalable fabrication protocol simultaneously reconciles favorable thermo-moldability and superior comprehensive performance of regenerated cellulose, and paves a promising pathway toward the utilization of lignocellulosic biomass as a substitute for nondegradable petrochemical plastics. Download: Download high-res image (201KB) Download: Download full-size image