Cellulose–protein supramolecular entangled networks enable bioplastics with ultrahigh strength and broad-temperature stability

Abstract Developing bioplastics that combine high mechanical robustness, structural stability across a broad temperature range, and non-petrochemical origins remains challenging. Herein, we report an entirely biomass-derived supramolecular bioplastic (BS–bioplastic) fabricated from cellulose and soy protein isolate via network reconstruction. Enabled by dense hydrogen-bonding interactions and an entangled supramolecular architecture, BS–bioplastic exhibits a tensile strength of 125.85 ± 3.16 MPa and a flexural modulus of 8.30 ± 0.22 GPa, while remaining structurally stable from − 196 to 180°C. After exposure to − 196°C for 30 min or 180°C for 2 h, it retains its intact morphology and a tensile strength exceeding 85 MPa—performance that, to the best of our knowledge, has not been achieved by either bio-based or petrochemical plastics. BS–bioplastic further allows ethanol-assisted programmable three-dimensional shaping and undergoes complete biodegradation under natural conditions. Economic analysis suggests its potential for scalable production, recycling, and reuse. This work demonstrates a feasible route to high-performance bioplastics derived entirely from biomass and establishes BS–bioplastic as a sustainable structural material for future applications.