Chemical Resistance Evaluation of DLC Thin Film Deposited on Polycarbonate Substrate Versus Acetone and Sodium Hydroxide

The aim of this study was evaluated the chemical resistance of diamond like carbon deposited on polycarbonate substrate. For this purpose, plasma etching treatment using argon and oxygen gases at various times were applied on the surface of polycarbonate substrates. Then the effect of O2 and Ar plasma pretreatment on wettability and surface chemical bonding of the polymers were investigated by water contact angle analyzer and Fourier transform infrared spectroscopy methods, respectively. Diamond-like carbon (DLC) thin film was deposited on the etched polymers by Radio Frequency- Plasma Enhanced Chemical Vapor Deposition (RF- PECVD) method using gas mixture of CH4 and Ar. The adhesion of the DLC films was investigated by tape test. Chemical stability of the coating was evaluated by exposing the samples under to acetone and sodium hydroxide solutions. The results showed that plasma etching with O2, because of formation of hydroxyl group and consequently more reduce in contact angle, were the most effective pretreatment method for improving the adhesion of the DLC film on the polymer surfaces. Study of the raman spectra peak intensities indicated that deposition of the DLC thin film improved chemical resistance of polycarbonate substrate after the exposing to acetone and sodium hydroxide solution.