Fabrication of amphiphilic self-healing coatings with high mechanical properties and their antifouling performance

A self-healing antifouling coating with excellent mechanical strength was prepared via a simple "one-step" method. A series of well-designed amphiphilic block copolymer polydimethylsiloxane-poly(2-(dimethylamino) ethyl methacrylate) (PDMS-PDMAEMA) synthesized by atom transfer radical polymerization was introduced to the self-healing polydimethylsiloxane-based polyurethane (PDMS-PU) system, which was further zwitter-ionized during solidification. The slight swelling resulting from zwitterionic segments promoted the contact fusion rate of the mechanically damaged parts, which improved the underwater self-healing ability of the resulting coating. The PDMS segments in both amphiphilic polymer and PU were entangled with each other to form a semi-interpenetrating network while the zwitterionic segments migrated externally when being immersed underwater, thus a micro-phase separation structure was obtained for antifouling coating. Qualitative and quantitative tests have also proved that the coating can significantly resist the adhesion of proteins (156 mu g/cm2 vs 14 mu g/cm2) and marine microorganisms (425 x 103 n/cm2 vs 12 x 103 n/cm2). In addition, the organically modified montmorillonite (MMT) effectively improved the coating's mechanical properties via coordination bonding, as the resulting coating's fracture strength was increased by 50 % compared with the initial PU coating. In this study, an inherent problem in underwater self-healing antifouling coatings is solved perfectly, that is to achieve self-healing properties without loss of mechanical properties, which provides inspiration for the research and development of novel self-healing antifouling coatings.