Biodegradable, recyclable, waterproof, antibacterial and high-strength supramolecular plastic fabricated from lignin derivatives

Lignin and lignin derivatives have a wide range of properties, such as high thermal stability, oxidation resistance, biodegradability, antibacterial activity and adhesion, which enable them to be widely used in the production of a variety of functional materials. However, producing biodegradable plastics that are recyclable, water-resistant, and with excellent mechanical strength, remains a significant challenge. Herein, we report a novel strategy to fabricate supramolecular polymers based on polyvinyl alcohol chains grafted with the lignin derivative syringaldehyde and then coordinated with the metal Cu2+. Experimental results reveal that the fabricated plastics are dynamically cross-linked with a high density of hydrogen bonds and hydrogen-bond-cross-linked hydrophobic domains. Notably, the resultant plastics exhibit a soft-hard adjustable capacity and the yield strength is increased from 59.6 MPa to 133.8 MPa after soaking and drying. Moreover, desired antibacterial properties, UV protection and degradability in the soil are demonstrated, providing a sustainable and green pathway for lignin derivatives.