Defluorination of polytetrafluoroethylene surface by hydrogen plasmaVesel, Alenka (Avtor) Lojen, Dane (Avtor) Zaplotnik, Rok (Avtor) Primc, Gregor (Avtor) Mozetič, Miran (Avtor) Ekar, Jernej (Avtor) Kovač, Janez (Avtor) Gorjanc, Marija (Avtor) Kurečič, Manja (Avtor) Stana-Kleinschek, Karin (Avtor) polytetrafluoroethylenefluorine depletionhydrogen plasmaVUV radiationsurface modificationhydrophilicDefluorination of polytetrafluoroethylene (PTFE) surface film is a suitable technique for tailoring its surface properties. The influence of discharge parameters on the surface chemistry was investigated systematically using radio-frequency inductively coupled H$_2$ plasma sustained in the E- and H-modes at various powers, pressures and treatment times. The surface finish was probed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The measurements of water contact angles (WCA) showed increased wettability of the pristine PTFE; however, they did not reveal remarkable modification in the surface chemistry of the samples treated at various discharge parameters. By contrast, the combination of XPS and ToF-SIMS, however, revealed important differences in the surface chemistry between the E- and H-modes. A well-expressed minimum in the fluorine to carbon ratio F/C as low as 0.2 was observed at the treatment time as short as 1 s when plasma was in the H-mode. More gradual surface chemistry was observed when plasma was in the E-mode, and the minimal achievable F/C ratio was about 0.6. The results were explained by the synergistic effects of hydrogen atoms and vacuum ultraviolet radiation.20202022-02-04 09:30:54Članek v reviji134842sl