Fully bio-based adhesive designed through lignin-cellulose combination and interfacial bonding reinforcement

Herein, lignin was functionalized to obtain quinonoid lignin (QL) and epoxidized lignin (EL), and cellulose was modified to be aminated cellulose (AC). A novel fully bio-based adhesive of QL-AC-EL with multiple cross-linked networks was designed based on Schiff base and addition reaction. Furthermore, the natural wood interface was activated by brushing aqueous solution of 3-aminopropyltriethoxysilane (APTES) to obtain a functional interface with many -NH₂ groups. Finally, the created QL-AC-EL was used as a specific adhesive to glue wood interface with abundant -NH₂ groups. The bonding performance was evaluated that the dry strength of the plywood specimens made from activated wood interface was 3.2 MPa, which increased by 123.8% than that of natural wood interface. It is amazing that the wet strength of plywood by using activated wood interface was 1.73 MPa, whereas wet bonding strength of natural wood was zero. The significantly improvement of the bonding properties should be caused by the covalent crosslinking between adhesive and activated wood interface, which plays an important role in the enhanced water resistance of the interfacial bonding stability. This work provided a new inspiration for the design of bio-based adhesives with excellent performance and water resistance from the interfacial chemical bonding perspective.