Development and screening of organic-inorganic hybrid coatings with anti-fouling properties for application on optical underwater instruments

For long term applications of optical underwater instruments in the marine environment, reduction of biofouling is of major importance. Coatings on glass substrates with antifouling properties have been developed, by the introduction of surface active functional groups in transparent organic-inorganic hybrid matrixes. Hybrid organic-inorganic coatings have been synthesised by hydrolysis and condensation of compositions containing functionally substituted (organo)silicon alkoxides RnSi(OR')(4-n), (R = alkyl, fluorine-substituted alkyl, phenyl; R' = methyl, ethyl; n = 0 or 1). A correlation between surface energy (contact angle with water) and marine anti-fouling properties is observed. Biological fouling is reduced but can not be completely prevented. Furthermore, it has become apparent that hybrid coatings with hydrophobic character are easy to clean, this in contrast to non-coated glass. Marine biofouling can also be decreased by the incorporation of inorganic biocides, such as boron oxide, copper and silver, in the coating matrix.