Lignocellulose-Induced Multiple Interfacial Coupling for High-Performance Self-Lubricating Wood-Epoxy Composites

This paper shows a method for constructing wood-epoxy-based solid self-lubricating materials through in situ regeneration of lignocellulose (LC) and an LC-assisted mechanical ball-milling process, achieving a “three birds with one stone” benefit while optimizing the interfacial microstructure of the matrix/filler. Specifically, natural wood was dissolved in deep eutectic solvents (DES), resulting in the deconstruction of cellulose micro-nanofibers and the structural cracking and in situ regeneration of lignin to produce LC. The LC and flake graphite was ball-milled together to exfoliate graphite through molecular interactions and π−π conjugation between both. Furthermore, functional groups (hydroxyls, ether bonds, and aromatic rings) in LC can replace segments of the epoxy resin (EP) 3D cross-linking network, enhancing its curing performance. The cellulose micro-nanofiber formed a continuous interdigitated network within the EP matrix, thus improving the stress transfer capability of LC–Graphite–PEEK–EP (LGP–EP) composites. The LGP–EP further eliminate the brittle characteristics of the EP matrix upon curing and exhibits a tensile strength of 17.87 MPa, a toughness of 0.44 MJ/m 3 , and an ultra-low friction coefficient of 0.074, demonstrating robust self-lubricating capability. This research opens up a green and efficient strategy for preparing high-strength, high-stability, and solid self-lubricating functional wood–polymer composites.