反応性ガスのＲ．Ｆ．放電プラズマによるガラス状カーボンの表面改質

Abstract

This investigation was conducted on the surface modification of glassy carbon (GC) by radio-frequency (13.56 MHz) glow discharge plasmas with the objective of investigating the effects of plasmas on GC surfaces and the mechanism of the elapse variations of the GC surfaces after the plasma treatment. The surface of GC was treated using reactive plasmas (CF4 and O2 plasma), and Ar plasma was used for comparison. The contact angles of water to the GC surfaces after the plasma treatment were measured and their elapse changes were investigated. Forthermore, the GC surfaces treated by plasmas were analyzed by ESCA and observed by SEM. Also, Raman spectra on the GC surfaces after the plasma treatment were measured. From these results, the following conclusions can be drawn. The contact angles to the GC surfaces vary with the treatment of CF4 (to 135°), O2 (to 4°) and Ar (to 15°) plasma from the contact angle on the untreated GC surface (90°). However, the contact angles are reduced from 135° to 120° in the case of CF4 plasma treatment, and are increased in the case of O2 (from 4° to 20°) and Ar (from 15° to 52°) plasma treatment in air at room temperature for 24 hours. The values of O/C (on the GC surfaces treated by O2 and Ar plasma) and F/C (on the GC surfaces treated by CF4 plasma) increase. The half value widths of the Raman band at 1360 cm-1 on the treated GC surfaces also increase, but their values are reduced in air at room temperature, as time passes. These findings suggest that the elapse changes in the contact angles to the GC surfaces after the plasma treatment would be induced mainly by the decrease in the number of fluorine atoms (in CF4 plasma treatment), hydrophilic groups containing oxygen (in O2 plasma treatment) and active radicals (in Ar plasma treatment).