A phytoalexin-inspired, natural product-based marine antifouling coating with synergistic active antimicrobial and passive anti-adhesive performances

The weak static antifouling performance and uncontrollable antifoulant release of silicone coatings remain persistent challenges. Inspired by the phytoalexin-mediated defense of Pterocarpus santalinus, which produces pterostilbene (PTE) to resist pathogen invasion, this paper reports a natural product-based synergistic antifouling coating that integrates active antibacterial and passive anti-adhesion functions. PTE is covalently grafted into a room-temperature-vulcanized silicone rubber (RTVS) network via reversible addition–fragmentation chain transfer (RAFT) polymerization, enabling controlled release through hydrolyzable covalent linkages and forming an active antibacterial layer. Concurrently, the incorporation of dodecafluoroheptyl methacrylate (12FMA) reduces the surface energy to 20.34 mJ·m⁻², creating a passive anti-adhesion layer that minimizes marine organism attachment. Importantly, A key novelty is multi-scale modeling confirms that the antifouling agent release follows Higuchi drug release model. Further molecular simulations reveal that a fraction of released molecules can be recaptured at the coating–water interface, forming a locally enriched region that maintains a high interfacial biocide concentration and explains the coating's long-term static antifouling efficacy; this newly identified interfacial zone is termed the “enrichment layer”. The coating achieves 98.36% anti-algal and 95.47% antibacterial efficiency, maintains excellent durability in a 240-day static marine field test, and shows favorable eco-safety in zebrafish-based toxicological evaluation. Overall, this work provides both a mechanistic insight and a practical strategy to overcome uncontrolled leaching and poor static antifouling in traditional silicone coatings.