PTFE surface etching in the post-discharge of a RF scanning plasma   torch: evidence of ejected fluorinated species
  The texturization of poly(tetrafluoroethylene) (PTFE) surfaces is achieved at atmospheric pressure by using the post-discharge of a radio-frequency plasma torch supplied in helium and oxygen gases. The surface properties are characterized by contact angle measurement, X-ray photoelectron spectroscopy and atomic force microscopy. We show that the plasma treatment increases the surface hydrophobicity (with water contact angles increasing from 115 to 155{\deg}) only by modifying the PTFE surface morphology and not the stoichiometry. Measurements of sample mass losses correlated to the ejection of CF$_2$ fragments from the PTFE surface evidenced an etching mechanism at atmospheric pressure. 
Thierry Dufour, Julie Hubert, Pascal Viville, Corinne Y. Duluard,   Simon Desbief, Roberto Lazzaroni, Fran\c{c}ois Reniers
cond-mat.other cond-mat.soft physics.ins-det physics.plasm-ph