  Among various surface modification techniques, plasma can be used as a source
for tailoring the surface properties of diverse materials. HDPE and
fluoropolymer surfaces have been treated by the post-discharge of an
atmospheric RF-plasma torch supplied with helium and oxygen gases. The
plasma-treated surfaces were characterized by measurements of mass losses,
water contact angles, x-ray photoelectron spectroscopy and atomic force
microscopy. This experimental approach correlated with an optical
characterization of the plasma phase allowed us to propose etching mechanisms
occurring at the post-discharge/polymer interface. We discuss how competitive
and synergistic effects can result from the oxidation and/or the roughening of
the surface but also from the excimer VUV radiation, the He metastable species
and the O radicals reaching the plasma-polymer interface.
