A Paintable, Scalable, and Durable Zwitterionic Hydrogel Coating for Enhanced Marine Antifouling Applications

Marine biofouling has been a severe challenge since the increase of maritime trade, significantly impacting the efficiency of ships by increasing drag, fuel consumption, hull corrosion, and even problems related to navigational safety and biological invasions. Commercial antifouling coatings have been developed for many years, but a satisfactory solution has yet to be found due to problems, such as high toxicity, environmental pollution, or high costs. Zwitterionic materials, with their superhydrophilic properties, demonstrate excellent resistance to nonspecific adhesion alongside good biocompatibility, making them promising candidates for marine antifouling applications. However, their superhydrophilic nature makes it difficult to anchor onto hydrophobic substrates, limiting their use. In this study, we presented a paintable, scalable, and durable antifouling coating system made by zwitterionic hydrogel (PSDA-Z), which was covalently attached to substrates through an acrylated epoxy resin primer coat and maintained antifouling performance even after 3 months of high-speed water shearing, high-pressure sandpaper abrasion, and sharp scratching. This PSDA-Z could also easily be applied on various substrates without specific treatments, including epoxy resin, poly(vinyl chloride) (PVC), polyurethane (PU), and wood. More importantly, this coating system achieved excellent antifouling performance comparable to self-polishing coatings (SPCs), the current industry standard in marine antifouling coating, in the Atlantic Ocean field tests for 3 months, suggesting its promise as an effective and ecofriendly alternative for marine antifouling applications.