High resolution XPS investigation of photocured films containing perfluoropolyether acrylates

The paper reports an XPS investigation on films obtained by photopolymerising new perfluoropolyether methacrylates as pure products or added in low amounts to a typical UV-curable resin (Bisphenol A bis-ethylether diacrylate). The structure of the fluorinated monomers is Rf-Rh type, where Rh = -CH(2)O-CO-NH-CH(2)-CH(2)-OCOC(CH(3)) = CH(2) while Rf = CF(3)-CF(2)O-(CF(2)O)(n)(CF(2)-CF(2)O)(m)-CF(2)- for monomer 1 (PM 890, m/n = 1.68), and Rf = Cl-CF(2)-CF(CF(3))-O-(CF(2)CF(CF(3))-O)(2)-CF(2)- for monomer 2. Quantitative evaluation of the different atomic ratios was performed using take-off angles of 45 and 10 degrees (very surface region) on both film sides, the one in contact with the glass substrate and the one exposed to air. The results obtained indicate strong fluorine enrichment on the air side of the films and a concentration gradient at the surface, while the glass side has a composition similar to the bulk. (C) 1999 Elsevier Science Ltd. All rights reserved.