Decoupling of Bonding Strength and Water Retention in Aqueous Wood Adhesive Inspired by Plant Cell

Abstract

Aqueous wood adhesives with both water retention and strong bonding strength are essential for wood industrial applications. However, the enhanced water retention of adhesive often suffers from low water resistance and bonding strength due to its increased hydrophilicity. Inspired by the water retention and mechanical support in plant cell, we develop a multifunctional biomass soybean meal (SM) adhesive by combining the rigid internal boron-nitrogen coordinated boronic esters structure for reinforcement with the flexible zwitterionic polymer for water retention. Such a design provides good dry (2.03 MPa) and wet shear (1.14 MPa) strengths and demonstrates durable adhesion in various harsh environments for up to 80 days. The adhesive exhibits the anticipated water retention property, extending the plywood shaping manufacturing time to 60 min due to the ability of the water-retaining polymer to convert free water into a bound state and suppress water evaporation. Additionally, the adhesive demonstrates a 10-fold increase in mildew resistance compared with the SM adhesive and exhibits good flame retardancy. This study presents a versatile and efficient approach for developing durable, water-retaining, and sustainable aqueous adhesives for various bonding techniques and shaping materials.