Influence of DBD Inlet Geometry on the Homogeneity of Plasma-Polymerized Acrylic Acid Films: The Use of a Microplasma-Electrode Inlet Configuration

Multiple vapor inlet systems have been developed to enhance the homogeneity of deposited polyacrylic acid films via medium and atmospheric pressure plasma technology. Different inlet systems were experimentally tested and optical reflectance spectrometry (OPS) was used to measure the differences in thickness of the films along the exposed surface. Standard deviations of more than 65% were reduced to less than 10%. COMSOL models point to the gas flow as the main contributor to the film homogeneity. OPS analysis of the best set-up shows a linear relationship between thickness and exposure time (100-200 nm/min). XPS C1s deconvolution indicates a preservation of +50% of the -COOH groups and a significant incorporation of other oxygen containing groups.