Visible Light-triggered Smart P(NIPAM-NVK)/PANI Antifouling Coating with Flexible Switching Between Photothermal-Photocatalytic Synergistic Antifouling Mechanisms and Fouling Release

Biofouling on submerged equipment causes significant economic losses and threatens human safety, necessitating the urgent development of innovative and effective antifouling technologies. Herein, a visible light-triggered thermoresponsive organic semiconducting copolymer, poly(N-isopropylacrylamide-N-vinylcarbazole) (P(NIPAM-NVK)) with a low critical solution temperature (LCST), is successfully synthesized via radical copolymerization of N-isopropylacrylamide (NIPAM) and N-vinylcarbazole (NVK). Compositing P(NIPAM-NVK) with photoactive polyaniline (PANI) created P(NIPAM-NVK)/PANI coatings with excellent multi-synergistic antifouling properties under visible light. Under visible light (λ > 400 nm) illumination, the P(NIPAM-NVK)/PANI composite coatings demonstrated strong light absorption and photothermal conversion properties, with elevated surface temperatures providing efficient photothermal antifouling. At the same time, P(NIPAM-NVK)/PANI photogenerated charge carriers, resulting in photocatalytic antifouling properties. By optimizing the composition of the composites, P(NIPAM-NVK)/PANI coatings with excellent antifouling performance are obtained (inactivation rates of 99.57% for E. coli and 99.95% for S. aureus). When the light is turned off, the surface morphology and wettability of the P(NIPAM-NVK)/PANI coatings gradually change, creating an unstable surface for bacterial adhesion (leading to fouling release efficiencies of 99%). The ability to easily switch between photoactive inactivation and dynamic biofouling release by simply applying light/dark conditions provides the basis for a simple solar-driven antifouling system.