Strong water-resistant, UV-blocking cellulose/glucomannan/lignin composite films inspired by natural LCC bonds

Lignocellulose multi-component films were fabricated using cellulose nanofiber (CNF), konjac glucomannan (KGM), and alkali lignin (AL). Covalent bonds among these three lignocellulose components were constructed with epichlorohydrin (EPI) to achieve chemical cross-linking, which inspired by lignin-carbohydrate complex (LCC) bonds in natural wood. Chemical cross-linking enhanced the mechanical properties of the composite films, the tensile stress reached to 110.47 MPa and the tensile strain reached to 8.27%. The presence of hemicellulose and lignin in composite films contributed to the functionalities of the films. The composite film with 20 wt% AL blocked over 99% of both UVA and UVB, the water contact angle reached 110.38°, and no obvious swelling behavior was observed after soaking in water for 180 days. Composite films with strong water-resistance and UV-blocking have great potential for the related application.