A Novel Universality Strategy for Fabricating Soybean Protein Adhesive with Excellent Adhesion Performance and Anti-Mildew

Abstract

Soybean meal (SM) adhesive is a promising alternative to petroleum-based ones. However, the poor water resistance, low bonding strength, and susceptibility to mildew limit its industrial application. Inspired by the micro-nano micelle structure's strengthening mechanism, we report a facile and green method to synthesize a high-performance soy protein adhesive by a dual cross-linking strategy. The in-situ self-assembled micelles of Benzyldodecyldimethylammonium bromide (BDAB) worked as dynamical physical crosslinking points, while 1,6-Hexanediol diglycidyl ether (HDE) acted as the flexible cross-linker. The BDAB micelles interact with protein chains via non-covalent electrostatic interactions improving the cross-linking density of the network system and the micelles with numerous amino cations exhibit efficient antibacterial properties. The as-obtained adhesive exhibits excellent mechanical properties and stable network structure, showing strong bonding strength and water resistance (2.22 and 1.25 MPa). Especially, the incorporation of HDE and BDAB endowed the modified SM adhesive with excellent antifungal and antibacterial ( E. coli and S. aureus ) performance, which significantly extends the storage life of the adhesive. Additionally, this work provides a new facile and universal strategy for fabricating a series of formaldehyde-free, environment-friendly, and renewable protein-based adhesives, which is a promising alternative to traditional adhesives in the wood industry.

Keywords: soybean meal adhesive, dual cross-linking strategy, micelle, water resistance, anti-mildew