Synthesis and characterization of di(ethylene glycol) vinyl ether films deposited by atmospheric pressure corona discharge plasma

Abstract

This study concerns plasma deposition by atmospheric-pressure corona discharge processing of di(ethylene glycol) vinyl ether (EO2V) as vaporized precursor. Plasma polymerized EO2V (pp-EO2V) thin films were coated using mixed Ar–O2 plasma as carrier gas onto plasma pre-treated surfaces of surgical-grade 316L stainless steel (SS 316L) coupons. The influence of plasma operating conditions on physical and chemical properties of pp-EO2V films was evaluated by contact angle measurements, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It was found that surface hydrophilic properties of the deposited film could be controlled by varying plasma deposition time, the carrier gas mixture and the applied plasma voltage. Spectral analyses of FT-IR and XPS affirm compositional changes occurred on the synthesized surface due to plasma activation of new polar and hydrophilic functional groups. There was a good correlation between the FT-IR results and the contact angle measurements. AFM images were used to investigate surface roughness and morphological aspects of the film. Rough estimate of the coating thickness was also provided based on AFM measurements. Stability of the film was evaluated by AFM before and after soaking in phosphate buffer saline solution.