Eco-friendly and efficient strategy for durable woody materials via in situ crosslinking of a quaternary ammonium-functionalized waterborne epoxy resin

Wood, as a natural lignocellulose material with multiscale porosity, serves as an excellent structural matrix for fabricating high-performance or functional composite materials. However, its wider application is severely hindered by inherent drawbacks such as poor dimensional stability and susceptibility to fungal degradation. In this work, we propose an eco-friendly and efficient strategy to fabricate wood-based materials with strong and long-lasting resistance to deformation and biodeterioration, aiming to promote the high-value utilization and sustainability of wood. A novel quaternary ammonium-functionalized waterborne epoxy resin (QWEP), featuring nanoscale particle size and high stability, was prepared and effectively infused into the porous structure of wood through vacuum-pressure impregnation. After in-situ curing reaction, the QWEP crosslinked network bearing quaternary ammonium salt (QAS) groups was formed and firmly anchored within the wood. The resulting QWEP modified wood composites achieved favorable dimensional stability and mechanical properties. The anti-swelling efficiency of composites reached 38.1%, while the tensile, flexural, and compressive strength increased by 42.6%, 45.8%, and 79.8%, respectively, compared with unmodified wood. Benefiting from the intrinsic antimicrobial activity of the grafted QAS groups, the composites also demonstrated outstanding antimicrobial efficacy against both bacteria and fungi. After three months of exposure to brown-rot and white-rot fungi, the composites showed an extremely low mass loss (approximately 3.0%) and no visible deformation.