Tough, stretchable, waterproof and biodegradable lignocellulosic films derived from fully physical interactions

Abstract

Cellulose films (CF) stand out among petroleum-based plastics due to their resource abundance, renewability, biodegradability and nontoxicity, but are hindered by the water sensitivity and poor mechanical performances. Herein, inspired by the cellulose/lignin network structure in natural bamboo, tough, stretchable and waterproof lignocellulosic film (LCF) was developed by embedding lignin into CF via physical impregnation. Lignin serving as natural binder was filled into the gaps between lamellar fibers of the swollen cellulose film and adhered onto cellulose fiber surfaces via intermolecular hydrogen bonding. The synergistic effect of densified structure and strong interfacial adhesion promoted the mechanical properties and water stability of the resulting LCF. The tensile strength of LCF reached to 73.37 MPa and was improved by 79.8 % when compared with CF. Even immersing in water for 30 d, LCF still presented remarkable mechanical performances with mechanical strength of 60.88 MPa, strain of 10.04 %. Synergistically, the incorporation of lignin also enhanced the thermal stability, antioxidant, UV shielding properties of LCF. Although the biodegradability of LCF was reduced by comparing with CF, it was still regenerable for sustainable usage. Therefore, this work provides not only a convenient method to fabricate lignocellulosic film, but also a high-performance full-biomass film that promises to replace nonbiodegradable petrochemical plastic.