Fluorine-Free Waterborne Polyurethane Coatings with Synergistic Fouling-Release and Contact-Killing for Marine Biofouling Defense

In this study, a novel waterborne polyurethane coating (BV-PDx) with dual-action (dynamic and static) antifouling efficacy was innovatively developed by incorporating polydimethylsiloxane (PDMS) as side chains and covalently grafting quaternary ammonium salts into the backbone. The highly flexible PDMS side chains not only reduce the surface energy and elastic modulus of the material but also endow the coating with superior dynamic fouling-release performance under hydrodynamic shear force. Simultaneously, the incorporated cationic active groups effectively address the limitations of pure siloxane systems in static environments through a nonleaching "contact-killing" mechanism. The coatings demonstrate broad-spectrum antifouling against Escherichia coli, Staphylococcus aureus, and Phaeodactylum tricornutum. Moreover, the mechanical properties can be effectively tuned by systematically adjusting the molecular weight of the PDMS segments. This research offers an innovative structural design strategy for the development of eco-friendly and durable marine antifouling materials adaptable to complex underwater environments.