Fabrication of biodegradable polyvinyl alcohol-based plastics toward technical lignin valorization

The fabrication of composite materials from lignin has attracted increasing attention to reducing the dependence of petrochemical-based resources on carbon neutrality. However, the low content of lignin in the biocomposites remains a challenge. Herein, industrial lignin is fractionated by an organic solvent to reduce its structural heterogeneity. Subsequently, the fractionated lignin samples are integrated with polyvinyl alcohol (PVA) to fabricate plastics characterized by uniform thickness and smooth surfaces. The resultant composite films exhibit tensile strength and strain up to 75 MPa and 1050%, respectively, which surpass state-of-the-art lignin-based bioplastics. The mechanism investigations reveal that the enhanced mechanical properties are due to the internal non-covalent interactions derived from the hydroxyl groups of lignin and PVA. Notably, the PVA/lignin films are biodegradable after 92 days' burial in soil. This study paves the way for the rational design of lignin-based biodegradable polymers as sustainable alternatives to conventional plastics.