Plasma surface treatment of poly(acrylonitrile) films by fluorocarbon compounds

Abstract

This paper concerns the use of the low-pressure plasma process to confer an hydrophobic character to poly(acrylonitrile) films, without altering their bulk properties. Plasma based fluorination processes using saturated fluorine compounds such as CF 4, C 6F 14 and mixtures CF 4/H 2 were used. Such treated polyacrylonitrile films were characterized by XPS analysis, infrared (ATR) spectroscopy and contact angle measurements. The use of CF 4 led to the fluorination of the film surfaces. Indeed, XPS spectra showed the presence of -CHF-, -CF 2- and -CF 3 groups. Moreover, the contact angle θ which was 63° for untreated PAN films increased to 115°. Fluorine incorporation in the PAN disappeared when hydrogen is added to CF 4. In the case of treatment by C 6F 14, fluorination was accompanied by a polymerization, as evidenced by XPS with the disappearance of the N 1s photopeak corresponding to the C≡N functions in PAN. By considering the deposition of F- containing layer thickness, it was possible in this latter case to follow the surface modifications by ATR-i.r. spectroscopy.