Novel hybrid anti-biofouling coatings with a self-peeling and self-generated micro-structured soft and dynamic surface.

We prepared hybrid antifouling coatings with a self-generated topographical microgel surface by mixing small surface-functionalized microgels with a self-peeling resin and a poly-functional cross-linking agent (axiridine). The microgels were prepared by copolymerizing acrylamide (AAm) and methacrylic acid (MAA). The resin is a random terpolymer made of methyl methacrylate (MMA), acrylic acid (AA) and triisopropylsilyl methacrylate (TIPSM). During the coating process, the microgels and terpolymer chains are cross-linked together to form a hard thin film. After it is immersed into sea water, the microgels dispersed and embedded on the film surface are swollen, generating small and soft bumps, and at the same time, the hydrolysis of TIPSM makes the surface layer hydrophilic, forming a thin layer of soft hydrogel. A combination of these two effects leads to a soft and dynamic topographical surface layer with many well-structured microgel bumps. Such a soft and dynamic surface is self-generating; namely, the hydrolysis of TIPSM eventually makes the terpolymer chains on the surface soluble so that a thin layer of them is gradually dissolved and washed away and the inner layer is further exposed to sea water. Here, both the self-peeling and topographically structured surface by small microgel bumps lead to antifouling properties. To test such a novel idea, we prepared a set of coatings with different microgel and TIPSM contents and evaluated their antifouling properties in a real marine environment. We found some optimal composition at which the coatings showed excellent antifouling properties in the field tests. Moreover, adding the microgels reduces the amount of expensive TIPSM required so that the coatings become more cost-effective, which is vitally important for industrial applications.