Ion beam analysis of the effects of radiation on the chemical etching of poly(tetrafluorethylene)

Abstract

Rutherford backscattering (RBS) and elastic recoil detection (ERD) have been used to characterize the effects of X-ray irradiation on the alkali etching of poly(tetrafluorethylene) (PTFE/Teflon). Etching of an irradiated (20 min MgK α X-rays) sample produces no RBS evidence of F surface loss (~ 150 Å depth resolution) while X-ray photoelectron spectroscopy (XPS) measurements (~ 30 Å sampling depth) show extensive F loss; thus the F loss in irradiated Teflon is limited to depths between 30 and 150 Å. In sharp contrast, etching of an unirradiated sample produces an RBS measured F loss to depths of 3000–4000 Å. ERD measurements show a similar H depth distribution, suggested to result from a water reaction during the dissolution of excess Na. An n-hexane rinse leaves a surface Na residue on X-ray irradiated material but subsurface on unirradiated etched material. The present results and those of previous adhesion studies show that the major factor affecting adhesion to Teflon is the mechanical interlocking of the porous etched surface.