High strength and flame retardant soybean polysaccharide-based wood adhesive produced by borate chemistry and crosslinking strategy

Development of wood adhesive combined with excellent bonding strength and water resistance is still challenging, particularly from sustainable and renewable polysaccharide–based materials instead of fossil resources. In this study, inspired by the periodate oxidation − adipic acid dihydrazide (ADH) crosslinking strategy and borate chemistry in plants, oxidized soybean polysaccharide complexed with borax (BSP) and then reacted with ADH via Schiff-base reaction to form the in-situ crosslinking skeleton, in which chitosan (CS) was introduced to improve the active sites. Through the interaction of covalent and hydrogen bond, the adhesive with multi crosslinking network (namely BSPC-ADH) was constructed. The resultant flame-resistant material showed excellent wet shear strength (0.9 MPa) and outstanding water resistance (86.9% residue rate), which met the requirements of indoor plate. This study provided a new method to develop renewable, potentially industrial-usable and environmental-friendly adhesive.