Modification of photocurable epoxides by new perfluoropolyalkylether alcohols for obtaining self-cleaning coatings

Abstract

Perfluoropolyalkylether (PFPAE) structures can be functionalized with alcoholic groups using an appropriate synthetic pathway: these new fluorinated alcohols can be used as surface modifying agents, through chain transfer mechanism in cationic UV-curing of an epoxy system. Notwithstanding their very low concentration (only ≤5 wt%), the fluorinated alcohols are able to induce a dramatic improvement to the surface properties of the films, without substantially modifying their curing conditions and their bulk properties, neither their transparency. As confirmed by Fourier Transform-Infra Red (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements, the fluorinated comonomers tend to concentrate selectively at the outermost layer of the epoxy UV-cured coatings, by spontaneously migrating to the free surface due to their low surface tension. The surface modification of the films depends on the concentration of the fluoroalcohols: coatings prepared with a concentration of PFPAE comonomer higher than 2 wt% are both hydrophobic and oleophobic. Moreover, thanks to their low surface energy (as low as 17 mN m−1) and reduced sliding angle (as low as 5°), photocured fluorinated copolymers show advanced coating performances such as anti-stain and self-cleaning properties.