The wetting behavior of plasma-treated nanocrystalline diamond films is studied for biocoating applications. The films are prepared from Ar-rich/N 2/CH 4 and Ar-rich/H 2/CH 4 mixtures by microwave plasma-enhanced chemical vapor deposition, and further treated by microwave hydrogen and oxygen plasma exposures separately. The hydrogen plasma treatment increases the surface roughness only slightly without a perceptible change in surface morphology and composition, and shows little improvement in wettability. In contrast, the oxygen plasma treatment produces fine protrusions and increases the oxygen concentration near the surface to ∼ 11 at.%, and then the contact angle of polar water and apolar 1-bromonaphthalene is drastically reduced from 92°and 4.7°-6.9°to almost zero degree, respectively. The extremely hydrophilic behavior of the oxygen-containing film is exclusively attributed to a great increase in the polar component of the apparent surface free energy up to ∼ 34 mJ/m 2.
All Science Journal Classification (ASJC) codes
- 化学 (全般)