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

Abstract

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.