Wood Cell Wall Structure-Inspired Polyurethane Adhesive with Excellent Bonding and Antibacterial Properties: Enabling Repeatable Processing of Plywood

The development and utilization of multifunctional biobased adhesives play a crucial role in achieving the green transformation of the adhesive industry. Inspired by the dynamic adaptation mechanism of wood cell walls, a high-performance polyurethane adhesive with a multi-level energy dissipation mode was successfully designed and prepared by constructing a dynamic network consisting of a rigid polyurethane (PU) framework and non-covalent cross-links. Different from the simple cross-linking design of traditional polyurethane adhesives with a single framework, this biobased adhesive innovatively constructs a multi-scale dynamic bond network. With the PU network serving as the rigid matrix for mechanical properties, efficient stress dissipation is achieved through the synergistic effect of three-level hydrogen bonds and polysulfide chains, endowing the adhesive with a high shear strength of 6.3 MPa. Moreover, by drawing on the antimicrobial activity of natural wood, a dual-effect synergistic mechanism combining physical and chemical antibacterial functions was established, which yields an excellent antibacterial efficiency of 98.9%. Particularly, the reversible nature of the dynamic network endows the adhesive with outstanding reprocessability, enabling the manufactured plywood to exhibit excellent bonding strength and toughness while allowing for its recycling and reuse. The entire adhesive preparation process is solvent-free, thus integrating environmental friendliness with economic efficiency. The sustainable biobased adhesive developed in this study not only provides a novel strategy for the upgrading of traditional polyurethane adhesives but also injects innovative impetus into the green and high-value development of the wood-based panel industry, demonstrating broad application prospects.