The surface oxidation of selected polymers using an atmospheric pressure air dielectric barrier discharge. Part II

In this paper, complementary to Part I published earlier herein, we report and discuss the results of surface treatment, using a dielectric barrier discharge (DBD), on various polymer films, which already contain intrinsically structurally bonded oxygen in their. structures prior to treatment. Surface analysis and characterisation of the materials studied were performed using X-ray photoelectron spectroscopy (XPS), contact angle measurement and scanning electron microscopy (SEM) before and following the DBD processing described. The influence of the discharge parameters, i.e. the energy deposited by the discharge at the electrodes, the inter-electrode gap and the treatment time, are related to the changes in the surface characteristics found post-processing. Our results show that polar functional polymers carrying intrinsically bound oxygen can be further oxidised on short exposures to a random filamentary dielectric barrier discharge of relatively low power running in air at atmospheric pressure. The outermost layer of the surface is modified very rapidly and remarkably uniformly within fractions of a second of DBD exposure. Moreover, there appears to be a limit in the level of oxidation which can be induced by such DBD treatment, i.e. the maximum level attainable is similar to45 at.% O. These data thus become complementary to our first series of experiments, as the degree of modification of the surfaces, in terms of oxygen content, seems to depend in the present case both on the "polarity" of the samples prior to treatment and on the respective chemical structure of the polymers. (C) 2003 Elsevier B.V. All rights reserved.