Wettability and surface chemistry of irradiated PTFE

Abstract

Abstract Low energy electron irradiation of PTFE induced fluorine depletion and introduction of oxygen on the surface. The effect on surface chemistry was shown to be dependent mostly on the amount of electrons reaching the sample, rather than on their energy. Changes in surface energy resulted in different wetting behaviors. The measurement of advancing water contact angles and the analysis of XPS C‐1s peak shapes showed that the least wettable portion of irradiated surfaces is made in most cases of CF 2 CF  units. When the treatment caused a nearly complete fluorine depletion, only isolated CF 2  or CF groups are present. Receding angle values decreased linearly depending on the amount of oxygen introduced on the sample during the treatment, suggesting the formation of strongly oxidized polymer islets. The invariance of contact angles with aging time indicated very low macromolecular mobility, probably related to extensive surface crosslinking.