Amphiphilic siloxane-polyurethane coatings.

摘要

Biological fouling of ships by marine organisms results in reduction of ship's speed and maneuverability and has serious consequences on mission performance. The non-toxic approach to combat biofouling is fouling-release (FR) coatings. FR coatings do not necessarily deter the attachment of marine organisms, but allow only a weak bond to form between marine organisms and the surface, so that fouling organisms are 'released' by the application of a shear force to the surface. Self-stratified siloxane-polyurethane coatings are a new approach to a tough FR coating system. In siloxane-polyurethane coating system, a low surface energy siloxane predominates on the surface while the tough and durable polyurethane forms the bulk of the coating system.;A challenge with the marine environment is that different organisms have different adhesion profiles. For example, it has been found that two types of marine algae, the green alga Ulva and diatoms e.g. Navicula show the opposite behavior with respect to adhesion to surfaces. Ulva typically adheres weakly to hydrophobic surfaces while Navicula adheres strongly to hydrophobic surfaces including silicone elastomers. Thus, designing coatings with a strictly hydrophilic or hydrophobic approach to combat biofouling should be avoided and an amphiphilic coating having compositional control over hydrophilic and hydrophobic components can potentially be used to more broadly resist marine biofouling.;It is a well-known fact that the lowest surface energy components of a solvent-cast block copolymer preferentially segregate or stratify to the surface. This phenomenon has been already used to create the self-stratified siloxane-polyurethane fouling-release coating system. The same concept can also be used to devise an amphiphilic siloxane-polyurethane coating system using amphiphilic siloxane polymers. Therefore, a siloxane polymer with pendant acid groups, a siloxane polymer with pendant polyethylene glycol chains and a polysiloxane triblock containing zwitterionic poly(sulfobetainemethacrylate) was incorporated into a polyurethane (PU) system and its biofouling performance was studied. The incorporation of these amphiphilic siloxane polymers into siloxane-polyurethane FR coatings shows promise for the development of unique coatings with improved FR performance.