Polyurethane coating with heterogeneity structure induced by microphase separation: A new combination of antifouling and cavitation erosion resistance

Cavitation erosion and biofouling are the most severe factors of metal materials fatigue failure and degradation in seawater. Herein, a series of hydrophobic fluorinated polyurethane coatings (SFPU-x) with various contents of fluorinated isocyanate prepolymer (FIP) were synthesized via a simple addition reaction for anti-cavitation erosion property combined with biofouling resistance. The microstructure and phase composition of as prepared coatings were analyzed by ATR-IR, SEM, TG, EDS and AFM. The addition of FIP increases the content of hard segments microregion and affects the microphase separation of the coating and induces the construction of surface heterogeneity microstructures. The static water contact angle and water absorption were measured as well. The antifouling tests were conducted using Nitzschia Closterium cell and the fluorescence labeled bovine serum albumin (FITC-BSA) as fouling models. Especially, the SFPU-5 coating with 5% FIP shows excellent antifouling and cavitation erosion resistance abilities due to surface heterogeneity microstructure, the attachment rates of FITC-BSA (1.1 %) and Nitzschia cell (1.3 %) far less than that of SFPU-0 coating (72.3 % and 85.1 %), respectively. Marine field test for 30 days also proven the antifouling properties of the SFPU-5 coating. In addition, there were no obvious holes and cracks on the surface of SFPU-5 after 10 h of cavitation, the cumulative mass loss were 2.7 mg and 2.9 mg in deionized water and in seawater, respectively.