Gallic acid modified aminated cellulose integrated polyethyleneimine to construct a phenol-amine chemical network for bonding wood

Abstract

Cellulose-based adhesives are becoming increasingly popular in the wood industry as an environmentally friendly alternative to formaldehyde-based resins. However, the development of highly water-resistant polymer structures is crucial for achieving reliable bonding with bio-based adhesives. Gallic acid (GA) was grafted onto aminated cellulose by covalent modification to obtain gallic acid functionalized cellulose (AC-GA). Using Schiff base reactions and Michael addition, phenolic amine networks were constructed by mixing AC-GA with polyethyleneimine (PEI) in a manner similar to insect cuticle sclerotization. The phenol-amine chemical network greatly facilitated the anchoring of rigid cellulose molecular chains, leading to a significant increase in crosslink density. Test results show that AC-GA/PEI has excellent bond strengths, with dry strengths of 2.05 MPa, hot water strengths of 1.76 MPa, and even boiling water strengths of 1.39 MPa. This work demonstrates that simulating the hardening process by using phenolic compounds and polyamine molecules can produce plywood with waterproof and stable bonding properties. Phenolamine networks offer interesting solutions for the development of green and aldehyde-free outstanding biomass wood adhesives.