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

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 CF4, C6F14 and mixtures CF4/H-2 were used. Such treated polyacrylonitrile films were characterized by XPS analysis, infrared (ATR) spectroscopy and contact angle measurements. The use of CF4 led to the fluorination of the film surfaces. Indeed, XPS spectra showed the presence of -CHF-, -CF2- and -CF3 groups. Moreover, the contact angle theta which was 63 degrees for untreated PAN films increased to 115 degrees. Fluorine incorporation in the PAN disappeared when hydrogen is added to CFS. In the case of treatment by C6F14, fluorination was accompanied by a polymerization, as evidenced by XPS with the disappearance of the N Is 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. (C) 1999 Elsevier Science B.V. All rights reserved.