Biomimetic flame retardant adhesive via combining polysiloxane, chitosan and vermiculite nanosheets inspired by nacre and arthropod cuticle.

The wood industry's dependence on traditional petrochemical adhesives, which pose environmental and health risks, has spurred research into sustainable alternatives. Sustainable bio-based polysaccharide materials show promise due to their inherent adhesive properties, despite challenges related to mechanical weaknesses and water resistance. Inspired by the hardening mechanisms of nacre and arthropod cuticles, we have developed a novel biomimetic flame-retardant HPA/OCTS/VMT NSs-NH adhesive. This adhesive uses oxidized chitosan (OCTS) to crosslink with hyperbranched polymers (HPA) and surface-modified vermiculite nanosheets ((VMT NSs-NH), conferring flame retardancy. Furthermore, the interfacial compatibility between the VMT NSs-NH₂ nanomaterials and the adhesive is enhanced through the mediating action of HPA, thereby promoting the homogeneous dispersion of the adhesive. Through Schiff base chemistry-mediated covalent crosslinking, VMT NSs-NH integrates with OCTS, forming a microphase-separated structure similar to marine arthropod cuticles. This combination yields a wood bonding strength of 1.7 MPa, a limiting oxygen index of 36.7 %, and excellent cone calorimetry test results, providing an environmentally friendly adhesive solution for the wood industry.