Dynamically Crosslinking Cellulose Nanofibers and Epoxy Soybean Oil toward Tough, Recyclable, and Degradable Bioplastics

Developing cellulose nanofiber-reinforced bio-based recyclable and biodegradable plastics can be a fundamental solution to the global accumulation of plastic waste. Herein, we present a bio-based supramolecular plastic with a "reinforced-concrete" architecture achieved through the establishment of cellulose nanofiber crosslinking network and dynamic boron oxide crosslinking between cellulose nanofibers (CNF) and epoxy soybean oil. Termed as DACNF-ESO, this bio-based supramolecular plastic exhibits an impressive tensile strength of ≈41 MPa while maintaining flexibility. After being subjected to a high temperature (150 °C) or water immersion for 7 days, the tensile strength of DACNF-ESO plastic remains superior to that of polyethylene (PE) plastics. The dynamic reversibility of boron oxide in DACNF-ESO plastic enables temperature adaptability and welding capability and allowed for multiple recycling cycles. Complete degradation of DACNF-ESO in soil without the generation of any harmful substances can be achieved within a period of 80 days. The present study offers a novel design principle for high-performance recyclable polymers as sustainable alternatives to conventional plastics. Moreover, both in vivo and in vitro tests demonstrate the exceptional biocompatibility of DACNF-ESO plastics, thereby expanding their potential applications in food, biological medicine, cosmetics, and flexible electronic substrates.