PTFE surface etching in the post-discharge of a RF scanning plasma torch: evidence of ejected fluorinated species

TL;DR

This study demonstrates that RF plasma torch post-discharge can texturize PTFE surfaces at atmospheric pressure, increasing hydrophobicity through morphological changes without altering chemical composition, and involves ejection of fluorinated species.

Contribution

It provides new evidence of fluorinated species ejection during PTFE surface etching in plasma post-discharge at atmospheric pressure.

Findings

Surface hydrophobicity increased from 115° to 155°

Surface morphology was modified without changing chemical composition

Ejection of CF₂ fragments indicates an etching mechanism

Abstract

The texturization of poly(tetrafluoroethylene) (PTFE) surfaces is achieved at atmospheric pressure by using the post-discharge of a radio-frequency plasma torch supplied in helium and oxygen gases. The surface properties are characterized by contact angle measurement, X-ray photoelectron spectroscopy and atomic force microscopy. We show that the plasma treatment increases the surface hydrophobicity (with water contact angles increasing from 115 to 155{\deg}) only by modifying the PTFE surface morphology and not the stoichiometry. Measurements of sample mass losses correlated to the ejection of CF$_2$ fragments from the PTFE surface evidenced an etching mechanism at atmospheric pressure.