Mussel-Inspired Catechol-Based Curing Agent for Ultra-Strong Underwater Adhesion of Epoxy Resin via Multiple...

Underwater adhesives are critical for marine engineering and biomedical applications, but face challenges in their bonding strength and processing complexity. Inspired by mussel foot proteins, catechol-based curing agents (D-A and D-C) were successfully synthesized via a one-step condensation reaction, while monophenol-based curing agents (D-L and D-P) were prepared as the control groups. The D-C curing system exhibited superior performance, demonstrating an exceptionally low curing activation energy of 38.29 kJ/mol (27.70% lower than that of D-P), an ultrahigh underwater adhesion strength exceeding 15 MPa on stainless steel substrates (125.89% improvement over D-P), and an antidispersion behavior with complete flow cessation within 30 min of underwater application. By integrating multiscale characterization techniques (SFG spectroscopy, DFT calculations, AIMD simulations, and XPS), we systematically elucidated the multisynergistic adhesion mechanism of the D-C system. The results reveal a highly cooperative water displacement, interfacial bonding, and bulk network locking mechanism that collectively governs the superior underwater adhesion performance.