Non-toxic, anti-fouling silicones with variable PEO–silane amphiphile content

Non-toxic silicone coatings with improved resistance to diatom slime formation were prepared by simple blending and curing with a poly(ethylene oxide) (PEO)–silane amphiphile: α-(ethylene oxide)₃Si-(CH₂)₂-oligodimethylsiloxane₁₃-block-poly(ethylene oxide)₈-OCH₃. Coatings were formed by blending varying levels (1, 5 and 10 wt%) into a room-temperature vulcanization (RTV), silica-reinforced silicone. The coatings were subjected to a series of biofouling tests, including exposure to Bacillus and Pseudoalteromonas bacteria and Cylindrotheca closterium diatoms, both individually and as a mixed community of Bacillus and C. closterium. Additionally, microfouling was evaluated upon exposure of the silicone coatings to natural seawater by submersion in the Atlantic Ocean for extended periods. Biofouling was assessed in terms of percentage of coverage, biomass and average thickness based on confocal laser scanning microscopy images. For all tests, silicones modified with 5 and 10 wt% PEO–silane amphiphile exhibited similarly high anti-biofouling behavior. In addition, silicone coatings modified with just 1 wt% PEO–silane amphiphile displayed a marked improvement on resistance to C. closterium diatom settlement compared to the unmodified silicone.