Coating composition for substrates immersed in water

A coating composition comprising

• a) seawater-hydrolyzable groups covalently linked to an acrylic polymer, which seawater-hydrolyzable groups are capable of undergoing hydrolysis or ion-exchange when exposed to seawater, rendering the polymer partially soluble or dispersible in seawater, and
• b) zwitterionic groups covalently linked to the acrylic polymer
• wherein the molar ratio of the seawater-hydrolyzable groups a) to the zwitterionic groups b) is 0.1 or higher,
• wherein the seawater hydrolyzable groups are selected from
• the group consisting of non-metal salt groups, metal salt groups, silyl ester groups, and mixtures thereof, and
• wherein the non-metal salt groups covalently linked to the acrylic polymer are
• selected from the group consisting of quaternary and acid salts of dialkylaminoalkyl(meth)acrylates, quaternary and acid salts of dialkylaminoalkyl(meth)acrylamides, N,N-diallyldialkyl ammonium halide, (3-methacryloylamido)propyl trimethylammonium halide salt;
• (3-acryloylamido)propyl trimethylammonium halide salt;
• (3-methacryloylamido)propyl trimethylammonium sulfonate salt, (3-acryloylamido)propyl trimethylammonium sulfonate salt, (3-methacryloyl)propyl trimethylammonium sulfonate salt, (3-acryloyl)propyl trimethylammonium sulfonate salt, and
• amine and phosphine salts of polymerizable unsaturated carboxylic and sulphonic acids
• wherein the silyl ester groups covalently linked to the acrylic polymer are selected from the group consisting of triisopropylsilyl (meth)acrylate, triisobutylsilyl (meth)acrylate, triphenylsilyl (meth)acrylate, and t-butyldiphenylsilyl (meth)acrylate.