A spider-silk-inspired soybean protein adhesive with high-strength and mildew-resistant via synergistic effect of MXene nanosheets and chitosan

Biomass adhesives show great potential in developing environment-friendly wood-based panel industry. Among them, soybean protein isolate (SPI) adhesives have a wide source of raw materials, but exploring high-strength, water-resistant, mildew-proof soybean protein-based adhesives remains a tremendous challenge. Inspired by the spatial structure arrangement of spider silk in nature, a facile and efficient bionic approach is adopted to prepare soybean protein adhesive with excellent overall performance by introducing chitosan (CS) and MXene nanosheets in soybean protein. The addition of MXene nanosheets is expected to form the β-sheet crystalline conformation of spider silk, which contributes to the formation of a tightly cross-linked adhesive system that hinders the penetration of moisture. Compared with the 1-SPI adhesive, the prepared 5-SPI/CS/MXene adhesive shows an increase of 175% in wet shear strength (1.76 MPa), indicating excellent adhesion strength and water resistance. Besides, the addition of CS benefits to improve the dispersibility of MXene in the adhesive system. Therefore, the synergy of MXene and CS significantly improves the strength, water resistance of the adhesive and increases the storage time from 7 d to more than 50 d. This research would provide a new idea for the preparation of biomass-based adhesives.