Chemical Modification of Diamond Surfaces with Fluorine-Containing Functionalities

Photolysis of perfluoroazooctane with diamond, such as diamond powders, films and nanodiamond films, led to a chemical modification of the surface so that perfluorooctyl functional groups could be introduced, and was confirmed by FT-IR, XPS, Raman and TOFSIMS measurements. The diamond films modified with fluorine moieties showed an improvement in frictional properties and a reduction of surface energy, which was evaluated by the contact angle with water compared with pristine diamond and nanodiamond films. The contact angle and friction coefficient of a chemically modified diamond film are 118° and 0.1, respectively. In the case of modified nanodiamond films, contact angle measurements showed a highly water-repulsive behavior, to be valued as 124° against water. The results of the values of water contact angle depending on irradiation time are consistent with those of the F/C ratio of fluorinated nanodiamond films monitored with XPS.