A high-performance bio-based adhesive comprising soybean meal, silk fibroin, and tannic acid inspired by marine organisms

The sustainable development of high-performance bio-based adhesives is both important and challenging for the wood industry. Herein, inspired by the hydrophobic property of barnacle cement protein and the adhesive property of mussel adhesion protein, a water-resistant bio-based adhesive was developed from silk fibroin (SF) rich in hydrophobic β-sheet structures and tannic acid (TA) rich in catechol groups as reinforcing components and soybean meal molecules rich in reactive groups as substrates. SF and soybean meal molecules formed a water-resistant tough structure through a multiple cross-linking network including covalent bonds, hydrogen bonds, and dynamic borate ester bonds constructed by TA and borax. The wet bond strength for the developed adhesive achieved 1.20 MPa, exhibiting its excellent application capabilities in humid environments. The storage period of the developed adhesive (72 h) was 3 times that of pure soybean meal adhesive owing to the enhanced mold resistance of the adhesive by TA. Furthermore, the developed adhesive demonstrated excellent biodegradability (45.45 % weight loss in 30 days) and flame retardancy (limiting oxygen index of 30.1 %). Overall, this environmental and efficient biomimetic strategy provides a promising and feasible route to develop high-performance bio-based adhesives.