Improving the coating and prepressing properties of soybean meal adhesive by constructing a biomimetic topological structure

Abstract

Developing a soy protein-based (SP) adhesive with robust coating and prepressing properties for broad applications in wood-based panels presents a challenge. In this study, a “bond-stitch” topological structure was constructed in a SP adhesive to improve coating ability and prepressing bond strength by incorporating dopamine-grafted sodium alginate (SD) as stitching materials and zinc sulfate (ZnSO4) into soybean meal–polyamide–epichlorohydrin (SM/PAE) adhesive. Abundant catechol groups on SD enhance the interfacial interaction between the adhesive and wood, and the topological entanglement of SD and the SM/PAE covalent network enhances the cohesion of the adhesive, synergistically endowing the adhesive with excellent prepressing intensity (0.83 MPa) and wet shear strength (1.09 MPa). Simultaneously, the improved initial adhesion and the suitable viscosity result in its excellent coating performance. The combination of ZnSO4 endows the adhesive with satisfactory antibacterial activity and mildew resistance. This method exhibits considerable potential for application in bio-based adhesives, hydrogels, and composites.