A solvent-free route to fully recyclable, high-performance cellulosic plastics

Abstract

The processing of biopolymers like cellulose into high-performance materials is critical for a circular economy but is hindered by strong hydrogen bonds, impeding solvent-free approaches. Herein, an intrinsic plasticization strategy subverts this limitation, creating a polymer-small molecule eutectic system from a cellulose derivative at an unprecedented concentration of 80 wt%. This binary system is a thermally reversible melt that solidifies into a robust film. The eutectic environment facilitates a catalyst-free, in situ crosslinking with epoxidized soybean oil, yielding a fully bio-based material with tunable mechanics and stability. The material's properties are governed by a dynamic network, imparting thermoset-like robustness with thermoplastic-like processability, enabling thermal welding and perfect closed-loop recycling. Its versatility is demonstrated in applications including high-performance adhesives, barrier layers for paper packaging, and as a host matrix for fluorescent anti-counterfeiting inks. This work thus establishes a new, fundamentally simple design principle for the valorization of intractable biopolymers into advanced, sustainable materials.