Biomimetic nacre-inspired multilayer lignocellulose-graphene composite films with high strength, toughness, and self-lubricating properties

Traditional lignocellulose-based composite films, due to the random arrangement of the matrix and lubricating domains, fail to establish effective load-transfer networks and continuous lubrication pathways, thereby exhibiting inferior mechanical and tribological properties. Inspired by the ordered multilayer structure of nacre, highly dispersible graphene was prepared via intercalation and exfoliation using 1-hexadecyl-3-methylimidazolium chloride ionic liquid and subsequently blended with lignocellulose to form a crosslinked “brick-mortar” network. A nacre-mimetic multilayer composite film was then fabricated through vacuum-assisted directional deposition. Compared with LC, the LCIGP exhibits a simultaneous enhancement in mechanical strength (90.8 MPa), toughness (5.56 MJ/m 3 ), and self-lubricating properties (coefficient of friction of 0.106), with its tensile strength up by 58.7% and toughness by 71.6%, together with a 69.3% reduction in friction coefficient. Molecular dynamics simulations showed that the ionic liquid-functionalized graphene strengthened interfacial interactions with the lignocellulose matrix and increased the number of hydrogen bonds, with the simulated mechanical and tribological properties confirming the experimental results and providing further molecular-level understanding of the reinforcement and self-lubrication mechanisms.