Copolymer films containing amphiphilic side chains of well-defined fluoroalkyl-segment length with biofouling-release potential

Abstract

Novel methacrylate copolymers containing polysiloxane (SiMA) and mixed poly(ethyleneglycol)-perfluorohexyl side chains (MEF) were synthesised and dispersed as surface-active additives in crosslinked PDMS films. The amphiphilic behaviour of the copolymers caused surface reconstruction in water which was characterised by dynamic and static contact angle measurements and angle-resolved X-ray photoelectron spectroscopy (XPS) analysis. The XPS CF₂/OCH₂ ratio between the hydrophobic fluoroalkyl segments and the hydrophilic oxyethylenic segments was high (15/64) for the copolymer richest in MEF (93 mol%), which also had a high percentage of surface fluorine (∼30%). By contrast, an especially low CF₂/OCH₂ ratio (0/16) and a low percentage of surface fluorine (∼2%) were identified for the copolymer poorest in MEF (14 mol%). Such large differences in surface chemical composition reflected different antifouling and fouling-release properties against the green macroalga Ulva linza. Generally, the films containing the copolymer with the smallest MEF content were able to resist the settlement of zoospores better than those with a high MEF content and had a superior release of sporelings (young plants).