Nature-inspired silicone-polythiourethane coatings based on capsaicin analogue for marine biofouling control

Capsaicin analogue, as natural product analogues, have demonstrated significant anti-fouling effects. However, few studies have explored the fluorescence properties of capsaicin in marine biofouling control. A novel capsaicin analogue, N -(2-ethoxynaphthalene)-acrylamide (NEA), was successfully synthesized through a Friedel-Crafts alkylation reaction. A series of nature-inspired silicone-polythiourethane coatings based on capsaicin analogue, denoted as PP-NEA-x, were prepared via a thiol-ene click reaction. Due to the polythiourethane matrix, these coatings exhibited excellent mechanical properties. In addition to the fluorescent response of NEA to the UV light in seawater, the typical capsaicin backbone imparts antifouling properties. Owing to the synergistic effects of approach-avoidance mechanism and fluorescence characteristic of NEA, silicone-polythiourethane coatings with fouling-release properties achieved an anti-attachment rate of above 90 % against Chlorella and mussel byssus proteins. Furthermore, the coatings demonstrated outstanding environmental compatibility, as confirmed by Artemia salina biotoxicity tests. These results suggest that the PP-NEA-x coatings represent a promising alternative to conventional antifouling materials, offering a combination of environmental sustainability, enhanced mechanical performance, and antifouling efficacy. • A nature-inspired silicone-polythiourethane coating based on capsaicin was synthesized. • The adhesion strength of all coatings exceeded 1 MPa. • The coating exhibited excellent antifouling ability against microalgae and mussels. • The coatings were preliminarily proven to be environmentally friendly.