Surface analysis of hydrophobicity of Thai silk treated by SF6 plasma

Hydrophobicity of Thai silk has been improved by plasma treatment using SF6 gases discharged by an inductively coupled plasma (ICP). The plasma was generated under a pressure range of 1.3–40.0 Pa while the RF power input is in a range of 20–100 W. A single RF compensated Langmuir probe and optical emission spectroscopy (OES) were used for the plasma diagnostics.The mechanisms responsible for the hydrophobic behavior were evaluated by SEM, X-ray photoelectron spectroscopy (XPS), attenuated total reflection (ATR) infrared spectroscopy, and were compared with quantum mechanical calculation. ATR-IR detected slightly changes for the peak intensities of the bands located in the frequency region of 1000–1050 cm− 1. XPS analysis results show the presence of CF–CF group as the increment of C/F ratio with increasing pressures. The results also agree with the density functional calculation. A fluorine radical shows the deposition by CH + F− → CF + H− reaction.