A Coral Shell-Inspired Biomimetic Soy Protein Adhesive Toward Electromagnetic Shielding Wood-Based Composites

The development of multifunctional bio-adhesives that are electrically conductive, flame-retardant, and electromagnetic shielding is crucial for advancing next-generation wood-based composites. However, to date it remains a significant challenge to achieve such functionalities in adhesives while maintaining their strong adhesion. This study draws inspirations from the microstructure and properties of coral shells, and proposed a multiphase engineering to prepare a multifunctional soy protein isolate (SPI) adhesive (SPI/PA@G) by introducing a hierarchical polyaniline/phenylphosphonic acid aggregates-loaded graphene nanoplatelets (GNPs) hybrid. Because of the presence of polyaniline/phenylphosphonic acid aggregates, the designed SPI/PA@G adhesive exhibits remarkable flame retardancy with a high limiting oxygen index value of ≈39.4%. Because the GNPs in the adhesive form a highly conductive network on wood particles surfaces, as-prepared wood-based composite achieves an electrical conductivity as high as 43100 S m^-1, and gives rise to an electromagnetic shielding effectiveness of 52.1 dB. In addition, multiple crosslinking interactions endow the SPI/PA@G adhesive with excellent bonding strength, as reflected by a high flexural strength of 19.7 MPa for the wood-based composite. This study offers a new approach to the design of multifunctional adhesives and their advanced wood-based composites, which holds great potential for real-world applications in creating advanced functional wooden products and beyond.