Photochemical Stability of Partially Fluorinated Acrylic Protective Coatings. 2. Copolymers of 1H,1H,2H,2H-Perfluorodecyl Methacrylate with Unfluorinated Acrylic Esters

The photochemical stability of a series of copolymers of 1H,1H,2H,2H-perfluorodecyl methacrylate (XFDMA) with acrylic or methacrylic unfluorinated esters has been investigated under artificial solar light irradiation. Molecular and chemical changes induced by the light treatment were monitored by weight loss and gel content determination, size exclusion chromatography, and Fourier transform infrared spectroscopy. In XFDMA/methyl acrylate the degradation mainly occurs on the tertiary position of the acrylic units, followed by extensive chain scissions. In the copolymers with butyl acrylate, butyl methacrylate, and lauryl methacrylate, the XFDMA units are not affected by oxidative degradation reaction, and the mechanism of degradation is influenced by the specific reactivity of the unfluorinated comonomer. For these samples the principal degradation effect is the cross-linking of the polymer structure promoted by radicals formed on the alkyl side groups, and it is only partially attenuated by the fluorinated units.