Zwitterionic siloxane-polyurethane fouling-release coatings

An approach to the design of polyurethane coatings having amphiphilic/zwitterionic surfaces via a self-stratification approach has been explored for marine non-fouling applications. Zwitterionic materials such as poly(sulfobetaine methacrylate) poly(SBMA), are used as non-fouling materials due to their protein resistance properties. ABA-type triblock copolymers, poly(SBMA)-block-PDMS-block-poly(SBMA), having PDMS as the central block and poly(SBMA) as the flanking blocks with secondary amines at the junction points were synthesized using ring opening equilibration polymerization (ROEP), Michael addition and atom transfer radical polymerization (ATRP). A series of triblocks were synthesized and incorporated into a polyurethane coating system and were evaluated for water contact angle (WCA), surface energy (SE) and pseudobarnacle adhesion (PB). The fouling-release (FR) performance of the coatings was evaluated in the laboratory using a suite of representative marine organisms. The coatings showed excellent FR performance toward the bacterium Halomonas pacifica and the diatom (microalga) Navicula incerta while the bacterium Cellulophaga lytica and sporelings of the green macroalga Ulva linza showed a relatively higher affinity for amphiphilic coating surfaces when compared to a series of standard control coatings.