Cationic, hydrolysable side-chain regulated self-renewal brush copolymers for antibacterial and antifouling marine coatings

Copolymers with quaternized poly(lauryl methacrylate)-b-poly(2-(N,N-dimethylamino) ethyl methacrylate) (PLMA-b-PDMAEMA) as the side chain, polycaprolactone (PCL) and siloxane bridged with hexamethylene diisocyanate (HDI) as the main chain were developed for antifouling marine coatings. With the hydrolysis of the quaternized PLMA-b-PDMAEMA and the degradation of PCL in seawater, the outmost surface of the coating peeled off by water shearing force. By exploring the co-effects of side chains, PCL and siloxane at varying contents, it was found that coatings with higher content of side chains tended to yield better surface hydrophilicity, faster surface self-renewal speed and lower protein adsorption amount. However, coatings with higher content of siloxane demonstrated stronger antibacterial abilities, even though they possessed less hydrophilicity and lower surface renewal speed. In-lab tests showed that the antibacterial rate of the coating can reach 99.7 % against E. coli and 99.6 % against S. aureus. And the lowest adsorption amount of bovine serum albumin was 36 μg/cm². Marine field tests revealed that most of the surface area of the properly designed coatings was clear of marine organisms during ∼330 d of testing.