| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Wednesday Sessions |
| Session TF-WeP |
| Session: | Thin Films Posters Session II |
| Presenter: | Kyoichi Terai, Tokyo Denki University, Japan |
| Correspondent: | Click to Email |
Diamond-like carbon (DLC) films have been investigated in domestic fields because of their many attractive properties. In especially, mechanical high hardness, low wear resistance and gas barrier property of DLC films can be mentioned as the dominant advantages. DLC coating has already applied to surface finishing technology of metallic molds, cutting tools and polyethylene terephthalate (PET) bottles. In recent, many researchers have reported the characteristics of chemical stabilities, blood compatibilities and cell affinities on the DLC films. Modification of the surface condition of DLC films has been rapidly expected to demand of the advanced medical care.
In order to improve the biocompatibility of DLC films, plasma treatment of oxygen (O2) and nitrogen (N2) gases are proposed on the DLC surfaces1). Surface conditions of the DLC films are delicate because bonds between carbon and oxygen are not so strong. The stability of effect of plasma treatment for DLC films has to investigate by systematic approach. In this study, we investigate that stability of the surface characteristics for time of O2 plasma treatment. DLC films were prepared on Si substrate by using r. f. plasma chemical vapor deposition ( r. f. plasma CVD ) in methane ( CH4 ) gas. After DLC films deposition, surface modification was carried out by O2 plasma. To evaluate stabilities of the plasma treatment on surface characteristics, surface conditions were analyzed by contact angle measurement and X-ray photoelectron spectroscopy (XPS). The cell affinity is estimated by in-vitro examination with a cell proliferation test using mouse-derived fibroblasts.
In case of contact angle measurement, DLC films without plasma treatments have water repellency and are almost constant. Hydrophilicity of surfaces immediately O2 plasma treatments is stables for several days, after that their change to the saturation value.
From the result of XPS, intensity ratio of oxygen and carbon peak on the surfaces of the DLC films without plasma treatment is increased as function of time. In contrast, the intensity ratio between oxygen and carbon is decreased with time in case of sample with O2 plasma treatments. The results revealed that adsorption and desorption of oxygen play important role to shift of the wettability in the plasma treatment on DLC films.
Reference
1. S. Murata, S. Ito, J. Mizuno, K. Hirakuri, K. Sato et., Phys. Ststus Soldi C9, No. 6 (2012) pp1439-1442.