Fully green, strong adhesion and multifunctional adhesive via construction of biomimetic mineralized structure

The urgent need to replace fossil-based adhesives has spurred the development of fully green alternatives. However, bio-based adhesives typically exhibit inadequate adhesion and limited functionality. Herein, we propose a simple and efficient biomimetic mineralization strategy to fabricate a fully green, strong adhesion, and multifunctional soy protein (SP) adhesive. Specifically, sodium alginate (SA) served as an organic template, inducing the formation of SA@CaCO 3 biominerals (with a mean particle size of 440.6 nm and lattice spacing of 0.238 nm) via interfacial molecular recognition. Tannic acid (TA) was then introduced to build a compatible interface between SP and SA@CaCO 3 by generating covalent/non-covalent interactions, thus constructing a biomimetic mineralized structure within the SP adhesive. This structure, through mineral reinforcement and ionic chelation, imparted the resulting SP-TA-SA@CaCO 3 adhesive with excellent dry and waterproof adhesion strengths, reaching 1.37 MPa and 1.20 MPa, respectively, significantly outperforming bio-based adhesives developed by other methods and meeting indoor use standards. The adhesive also exhibited a high Young’s modulus of 24.671 GPa. The biomimetic mineralized structure acted as a continuous thermal barrier network, enabling the SP-TA-SA@CaCO 3 adhesive to achieve good thermal stability and flame-retardant performance (level B 1 in GB 8624–2012). Furthermore, the polyphenol and mineral components endowed the adhesive with effective anti-mold performance after 360h. This work provides a feasible and versatile strategy for developing environmentally friendly, advanced, and functional plant-protein adhesive.