Competitive and synergistic effects between excimer VUV radiation and O radicals on the etching mechanisms of polyethylene and fluoropolymer surfaces treated by atmospheric He-O$_2$ post-discharge

TL;DR

This study investigates how VUV radiation and O radicals in atmospheric helium-oxygen plasma influence the surface etching of polyethylene and fluoropolymer, revealing complex interactions that modify surface properties.

Contribution

It introduces a detailed analysis of the combined effects of excimer VUV radiation and O radicals on polymer surface etching during atmospheric plasma treatment.

Findings

VUV radiation and O radicals have both competitive and synergistic effects on surface etching.

Surface roughness and oxidation are significantly affected by plasma components.

The proposed mechanisms enhance understanding of plasma-polymer interactions.

Abstract

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.