Sustainable bio-based polyurethane coating with integrated corrosion resistance and antifouling functions

Abstract

To meet the comprehensive requirements for anticorrosion and antifouling in marine engineering equipment, a combination of primer, connecting paint and topcoat is typically employed. This multilayer protective system must not only address the challenges of layered application but also resolve the compatibility issues between coatings at each level. Consequently, the development of an integrated protective coating that possesses both anticorrosion and antifouling properties represents a new trend. This work reports the use of castor oil fatty amide (CFA) polyol modified silicon-based polyurethane coating (PPMC-x) to improve its marine corrosion resistance and anti-fouling performance. The long alkyl chains and trihydroxy crosslinking sites of CFA reduce the surface energy of the polyurethane coating and enhance its crosslinking density, which helps inhibit marine fouling adhesion and infiltration of corrosive media. Electrochemical impedance spectroscopy (EIS) shows that CFA significantly improves the corrosion resistance of the polyurethane coating. For PPMC-7, its low-frequency impedance modulus (|Z| _0.01Hz) remains at 1.5 × 10⁹ Ω·cm² after 40 days. The coating has effective antifouling properties against two different scales of fouling organisms: diatoms and mussels. The polyurethane coating prepared from biomass materials has significant effectiveness in inhibiting corrosion and preventing the adhesion of biological fouling. This work provides a theoretical foundation for the sustainable development of ship protective coatings.