Effects of Plasma Etching on Surface Modification and Gas Permeability of Bisphenol-A Polycarbonate Films

摘要

The surface fluorination of polycarbonate bisphenol-A thin films was carried out by treatment with plasma of sulfur hexafluoride/argon (SF6/Ar) using a radio frequency (RF) discharges. Effects of treatment time and SF6 concentration have been studied. Surface characterization was performed using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy with attenuated total reflectance (FT-IR/ATR), atomic force microscopy (AFM) and contact angle measurements. The effects of the surface modification on the carbon dioxide (CO2) gas permeation of the fluorinated films were evaluated. The results showed effective fluorination of all samples, with C-F, C-F2 and even C-F3 groups attached to the polycarbonate, depending on the treatment conditions. The presence of incorporated fluorine molecules absorbed into the polymer structure during treatment was also shown. The polymer films showed an increase of their surface roughness and a decrease in their surface tension due to the plasma treatment. Plasma fluorination also decreases polycarbonate CO2 permeability considerably. The films treated with the lower concentration of SF6 showed the highest barrier values; however, significant differences between the permeability values for the samples treated for different times were not observed.