Staghorn-Inspired Eco-Friendly Marine Coatings with Controlled Capsaicin Release and Temperature-Responsive Wettability for Robust Biofouling Defense

Marine antifouling coatings are designed to alleviate the pervasive marine biological pollution; however, existing environmentally friendly low-surface-energy coatings exhibit poor static antifouling performance, along with issues such as unstable antifoulant release and limited capability to remove adhered bacteria. Inspired by the self-protection mechanism of staghorn corals and ocean temperature variations, a novel coating named PDMS-P(NIPAM)10-P(CsAc)5, has been developed. By incorporating a novel copolymer of poly(N-isopropylacrylamide) (PNIPAM) and capsaicin into the silicone polyurethane side chains, the coating exhibits excellent synergistic antifouling performance by integrating temperature-responsive fouling release with the biocidal effects of capsaicin, effectively combining both active and passive antifouling strategies. Capsaicin is continuously and stably released through hydrolysis and adheres to the coating surface, exhibiting antibacterial efficacy of 99.03% against E. coli and 97.83% against S. aureus. Meanwhile, temperature-induced changes in the coating's wettability facilitate the detachment of bacteria from the surface. Furthermore, the coating exhibits exceptional properties in preventing protein and algae adhesion. It also exhibits excellent mechanical strength and self-healing capabilities with an adhesion strength of up to 2.49 MPa and a self-healing rate of up to 90.47%, highlighting its significant potential for marine antifouling applications.