A Cu₂O-based marine antifouling coating with controlled release of copper ion mediated by amphiphilic PLMA-b-PDMAEMA copolymers

To achieve prolonged and sustainable release of copper ion in Cu₂O-containing marine coatings, poly(lauryl methacrylate)-b-poly(2-(N,N-dimethylamino)ethyl methacrylate) (PLMA-b-PDMAEMA) diblock copolymers with different block ratios and molecular weights were synthesized by atom-transfer radical polymerization (ATRP) method. It was proved that the copolymers are able to coordinate with copper ion. And the surface wettability tests showed that the amphiphilic copolymers may undergo structure change in seawater. Taking advantage of the structure transformation and copper coordination abilities, the copolymer was employed to encapsulate Cu₂O for the preparation of antifouling coatings. A controllable and continuous release of copper ion from Cu₂O/copolymer coatings was then obtained. More importantly, it showed that higher PLMA/PDMAEMA block ratio exhibited better bactericidal rate. Actually, the bactericidal ability of the coating depends on the time duration of copper ion on the surface instead of the hydrolysis speed of the coating, in other words, the hydrophobic interaction of PLMA with the resin may play a major role in the antifouling performance of the marine coating. Self-polishing coatings Cu₂O/copolymer/polycaprolactone (PCL) were then prepared and applied for marine field test, the antifouling performances were proved to be comparable to that of the commercially available self-polishing coatings.