Surface Characterization of Hydrophilic Coating Obtained by Low-Pressure CH4-O2 Plasma Treatment on a Polypropylene Film

The use of surface treatments at industrial level is generalized as they allow obtaining a wide variety of properties such as soft in the touch, hydrophilic behavior, and biocompatibility. The use of low-pressure plasma techniques with organic gases or organic mixtures is an easy way to obtain surface coatings very small in depth through plasma-polymerization processes that can be assimilated to a plasma-enhanced chemical vapor deposition (PECVD) process. In this work, we have carried out a plasma-polymerization process on a polypropylene (PP) film to obtain a hydrophilic coating. To obtain this, the film surface has been treated on a low-pressure plasma reactor with a methane-oxygen fixture gas with a volume ratio of 80 : 20, respectively. The chemistry changes in the outermost layers of the deposited coating have been investigated with X-ray photoelectron spectroscopy (XPS). The different processes that take part as a consequence of the interaction between the plasma gas species and the PP film surface mainly drive to the deposition of an organic layer, which is functionalized with oxygen-based species as XPS study reveals. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2992-2997, 2009