Fabrication and characterization of optical, mechanical and chemical properties of diamond-like carbon thin film deposited on polymer substrate

Abstract

In this research, diamond-like carbon (DLC) thin films were deposited on polycarbonate (PC) substrates by a R.F. plasma-enhanced chemical vapor deposition method. Before film deposition, PC substrates were cleaned and activated by O2 plasma etching. The effect of O2 plasma etching on wetting angle, chemical structure of the surface and the morphology of the samples was investigated by a contact angle analyzer, Fourier transform infrared spectroscopy and atomic force microscopy, respectively. The adhesion, structure, surface morphology and topography of the films deposited on the PC substrates were investigated. The chemical stability of the thin films was evaluated by exposing them to acetone and sodium hydroxide. The effect of UV irradiation on the properties of the films was investigated. Chemical stability investigations showed that DLC thin film deposited on the PC substrate improved the chemical resistance of the PC against alkaline environment. After UV-radiation, the scratch resistance and light transmittance of the samples were increased and maintained constant, respectively. While, the uncoated PC showed a decrease in scratch resistance and light transmittance after UV-radiation. It was found that the gas barrier performance of the PC coated DLC is three times larger than that of the uncoated PC substrate.