Surface Modification of Polymers and Metal in Carbon Tetrafluoride Plasma

Abstract

The surface of the functional polymers listed in Table 1 and of aluminum was modified in CF₄ plasma generated with either radio-frequency (r. f., 13.56 MHz) or microwave (m. w., 2450 MHz) glow discharge. Samples were placed into the discharge field (on the grounded electrode) in the case of r. f. plasma treatment and were placed 13 cm below the cavity in the case of m. w. plasma treatment.
The results of contact an gle measurements, shown in Figs.4 and 5, prove that the polymer surfaces treated in CF₄ plasma become at least as hydrophobic as poly(tetrafluoroethylene)(PTFE) surfaces in very short treatment time. The modified surface layers contained a lot of fluorine atoms, most of them united with carbon atoms (Fig.8, Tables 3and 4).
However, a difference in the modifying process was discovered between r. f. and m. w. treatments. The r. f. -treated samples exhibited weight loss (Fig.1) and rough surface (Photo.1) because of etching. In contrast to this, deposits from CF₄ plasma were formed on the m. w. -treated samples.
Aluminum plates co ated with CH₄ plasma were exposed to CF₄ plasma. This is a new try to deposit the layers of graphite fluoride, which has the lowest surface energy, on metal surfaces by means of plasma treatment. The results of surface analyses suggest that this method is hopeful.