A Strong and Water-Retaining Biomass Adhesive Inspired by Tofu

Abstract

The poor mechanical strength and low water retention of biomass adhesives present significant challenges when substituting petrochemical adhesives in practical applications. Inspired by the colloidal gel structure in Tofu, the development of a high-performance protein-based adhesive derived from soybean meal (SM) oxidized by glucose oxidase (GOx) and calcium sulfate oligomer (CSO) is reported. The catalytic oxidation of sugars in SM by GOx produces active carboxyl groups, increasing active sites for calcium bridge (sugar-protein) formation in CSO. Concurrently, GOx disrupts the internal electrostatic equilibrium of SM, promoting the formation of an acid-induced colloidal gel-like network structure. This Tofu-like structures can effectively minimize water evaporation and significantly enhance the interfacial adhesion. Plywood bonded with the modified adhesive demonstrates a 129% increase in wet strength compared to unmodified counterparts. Additionally, the water loss rate of modified adhesive is reduced by 30.66% at 30 minutes, while maintaining 70.37% of its initial wet strength. This enzymatically mediated organic–inorganic hybrid structure represents a promising strategy for future development of sustainable biomass adhesives.