Xylan thermoplastics with closed-loop recyclability

Abstract

Xylan-derived packaging materials have gained considerable popularity owing to their renewability, non-toxicity, and biodegradability. However, thermoforming is challenging owing to its rigid structure and hydrogen-bonding network of the xylan molecular chain, which limits its large-scale production. Herein, a heat-processable xylan derivative, xylan cinnamate (XC), was synthesized via an esterification reaction in ionic liquids. The glass transition temperature of XC can be adjusted by the degree of substitution, ranging from 65 to 150 °C. XC plastics can be obtained by hot pressing and exhibit competitive mechanical properties, excellent water resistance, high transparency, and re-processability. Furthermore, the tensile strength of the XC plastics increased from 25 to 50 MPa after 365 nm ultraviolet (UV) irradiation because the double bonds of the cinnamon substituents were photodimerized under UV irradiation. Compared with commercial polyethylene packaging materials, XC plastics have suitable water vapour and oxygen transmittance, effectively protecting seeds under storage conditions. This study developed a novel strategy for preparing recycled xylan thermoplastics.