SURFACE ACTIVATION OF NONPOROUS PERFLUORINATED POLYMERS BY DEPOSITIONOF SILICA

A method to enhance the surface energy of non-porous films of three di fferent types of perfluorinated polymer [polytetrafluoroethylene with and without a perfluorinated modifier and poly(tetrafluoroethylene-co- hexafluoropropylene)] is described. The surface was activated by the d eposition of silica, produced in situ from SICl4 and water, without an y chemical degradation or modification of the polymer bulk. By adding perfluorohexane and 1,1,1,3,3,3-hexafluoroisopropanol as auxiliaries t o the SiCl4 and water in the gas phase respectively, extended silica l ayers with spherical morphologies could be generated, which were perma nently fixed to the films. By use of low voltage scanning electron mic roscopy (LVSEM) it was shown that the adhesion of the silica to the fl uoropolymers is due to its mechanical anchoring, ultimately resulting from the diffusion of SiCl4 and water into the polymer surface. (C) 19 98 Published by Elsevier Science Ltd. All rights reserved.