Spider silk-inspired high-performance soybean meal-based adhesive reinforced by greenly produced chitosan-functionalized boron nitride nanosheets

A facile and environment-friendly bionic strategy is developed to construct high-performance soybean meal (SM)-based multifunctional adhesives by using chitosan-functionalized boron nitride nanosheets (CS@BNNSs) as an alternative to β -sheet nanocrystals to mimic the structural characteristics of natural spider silks. CS@BNNSs were cost-effectively and greenly produced from bulk hexagonal boron nitride through chitosan-assisted mechanochemical exfoliation. Compared with the neat crosslinker-modified SM-based adhesive (MSM), the fabricated adhesive (MSM/CS@BNNSs) features remarkable improvement in mechanical performance, such as enhanced wet shear strength (1.31 MPa vs. 0.58 MPa), work of debonding (0.366 J vs. 0.186 J), and dry shear strength (1.96 MPa vs. 1.42 MPa). The outstanding performance is attributable to the dense covalent/non-covalent intermolecular interactions and good compatibility between CS@BNNSs and the SM matrix, which are beneficial to the dissipation and transfer of energy under loading. In addition, the MSM/CS@BNNSs adhesive exhibits noticeably improved flame retardancy and excellent anti-mildew performance compared with the neat SM-based adhesives, and its shelf life reaches up to 72 h. Such an advanced MSM/CS@BNNSs adhesive reaches the engineering resin level and possesses promising potentials for industrial applications. Overall, this facile and efficient spider silk-mimicking structural design strategy assisted by a green and low-cost mechanochemical exfoliation would provide endless inspirations for constructing and reinforcing multifunctional bio-based adhesives, elastomers, and plastic materials.