PLASMA FLUORINATION OF ORGANOSILICON POLYMERIC FILMS FOR GAS SEPARATION APPLICATIONS

SF6 plasma treatment using an RF discharge was carried out for the sur face fluorination of polytrimethylsilylpropyne (PTMSP) and polyvinyltr imethylsilane (PVTMS) films. Gas permeation of the fluorinated and unh eated films for O-2, N-2, He, H-2, CH4 and CO2 gases has been measured . Plasma fluorination increases the ideal selectivities of the PTMSP f ilms decreasing their permeances for all the gases measured, and does not affect the permeances and selectivities of the PVTMS films, The co mposition and chemical structure of the fluorinated polymer surface we re investigated using X-ray photoelectron spectroscopy (XPS) and F-19 nuclear magnetic resonance (NMR) spectroscopy. Within the range of the treatment parameters studied, permselectivity and surface composition of the fluorinated PTMSP films depend slightly on the treatment time and the density of the fluorine atom flux on the modified surface. The trimethylsilyl substituents are detached and carbon atoms are partial ly fluorinated during modification. The structure of the fluorinated l ayer contains crosslinks and unsaturated bonds.