Sustainable Marine Antifouling Coatings Based on Hydrolysis-Driven Self-Polishing and pH-Responsive Arbutin Release

Abstract

Marine biofouling necessitates durable, low-toxicity coatings. We developed a hydrolyzable polysiloxane-polyurethane acrylate nanocomposite combining surface self-renewal with pH-responsive natural antifoulant release. The polymer matrix, synthesized from polydimethylsiloxane, hexamethylene diisocyanate, and hydroxyethyl acrylate, contains ester side chains enabling gradual hydrolysis and self-polishing. Zeolitic imidazolate framework-8 loaded with arbutin (ZIF-8/Arb) and nano-SiO2 provided responsive antifoulant delivery and mechanical reinforcement. The optimized coating showed controlled mass loss (0.6 mg cm–2 over 60 days), strong adhesion (5B), high lap-shear strength (14.1 MPa), and excellent abrasion resistance (only 5° water-contact-angle drop after 20 sand-drop cycles). Hydrolysis continuously removed the fouling-prone surface layer, while ZIF-8/Arb released arbutin and Zn2+ under bacterial acidic microenvironments, minimizing unnecessary release. The coating achieved >99% antibacterial efficacy against Escherichia coli and Staphylococcus aureus, retained >90% activity after 30 days, inhibited Chlorell growth by >30%, and suppressed protein adsorption. In 35 day marine field tests, it exhibited sparse diatom settlement and negligible macrofouling. This work demonstrates that integrating hydrolysis-driven self-polishing with responsive natural-antifoulant release offers a sustainable antifouling strategy, providing design insights for durable, efficient, and eco-friendly polymer nanocomposite coatings with reduced biocide dependence.