Fine characterization of plasma‐polymerized films from a methane/air mixture

The plasma polymerization of methane/air mixtures was performed to produce a hydrophilic film on a substrate, and the obtained films were characterized with ellipsometry, elemental analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and contact-angle measurements. Fourier transform infrared revealed that the structure of the plasma-polymerized films changed with increasing film thickness; that is, an increase in the film thickness led to an increase in the absorbance ratio of the carbonyl band at 1664 cm−1 to the methyl band at 1385 cm−1. Although the contents of nitrogen and oxygen measured by elemental analysis changed with the film thickness, the contact angle and X-ray photoelectron spectroscopy atomic ratio of the films were independent of it. Nitrogen and oxygen were contained in the bulk more than on the surface of the films. Nitrogen and oxygen were copolymerized with methane, and the properties of the obtained films were similar to those of an amide compound. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3408–3414, 2006