Characterization of Nitrogen-Rich Coating Films with Atmospheric-Pressure Plasma Generated by Re-Entrant Microwave Cavity

The deposition and characterization of nitrogen-rich coating films using atmospheric-pressure plasma generated with a re-entrant cylindrical microwave cavity is presented. This system enables simple matching, stable plasma, and free space under the orifice of plasma steam. Allylamine and acetonitrile are employed as monomers, whereas argon is used as the carrier gas. The effective area of the hydrophilic coating film is 55 mm in diameter and the deposition rate is 10 nm min^-1. X-ray photoelectron spectroscopy measurements show that the surfaces of these films contain a high concentration of nitrogen atoms and primary amine groups. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry shows that the coating films have a large molecular weight (>200 kDa). The surface morphology is very flat (ca. 1 nm). The experimental results indicate that a highly cross-linked three-dimensional polymer matrix is formed and atmospheric-pressure plasma deposition is successfully achieved.