Enhancement of hydrophobic properties of HTV silicone rubber by CF4 plasma treatment

In this paper, a superhydrophobic surface of silicone rubber was fabricated by plasma treatment method. Modification of the surface chemistry under CF4 atmosphere at different times (3, 5, and 7 min) and powers (50, 75, and 100 W) of plasma process has been investigated. A superhydrophobic surface with contact angle of 151.3 degrees was obtained for plasma treated sample at 100 W for 7 min. X-ray photoelectron spectroscopy (XPS) results indicated that the surface fluorination of silicone rubber increased as the time and power of plasma exposure increased. Investigation of the F 1s and Si 2p spectra approved the formation of F-C and F-Si bands. Also, the roughness of the surface increased from about 42 nm for untreated to 55 nm for treated sample (7 min at 100 W) due to the emergence of the ceramic fillers in degraded silicone rubber matrix after plasma treatment. Both of the surface fluorination and roughness increment are the reasons of superhydrophobicity properties. Examination of the hydrophobic recovery by surface contamination method indicated that a contact angle of 101 degrees was recovered after 9 days.