Bio-inspired co-deposition strategy of aramid fibers to improve performance of soy protein isolate-based adhesive

Soy protein isolate (SPI)-based adhesives are abundant and environmentally benign materials, which have potential applications in many fields. However, the assembly of high-performance SPI-based adhesives for practical applications remains a great challenge. Here, inspired by the adhesion of marine mussels and ascidians, surface-modified aramid fiber (AF) with a high surface roughness and grafting degree was successfully developed by the catechol/polyamine (CAPA) and pyrogallol/polyamine (PGPA) co-deposition, and then used as a reinforcing agent to improve the performance of SPI-based adhesives. The much hydrogen and covalent bond between the side chain groups of SPI and the functionalized AF greatly improve the bonding strength and water resistance of the resultant adhesives. The wet shear strength of the plywood bonded by the resultant adhesive was improved by 133.3 % to 1.68 MPa. Moreover, the reactive catechol groups and pyrogallol groups endow the adhesive with contact intensified bactericidal activity. This study provides a new strategy for fiber surface functionalization, which has promising application in SPI-based adhesives.