| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS+AS+BI+SE-MoM |
| Session: | Atmospheric Plasma Processing: Fundamental and Applications |
| Presenter: | J. Hubert, Univ. Libre de Bruxelles, Belgium |
| Authors: | J. Hubert, Univ. Libre de Bruxelles, Belgium N. Vandencasteele, Univ. Libre de Bruxelles, Belgium T. Dufour, Univ. Libre de Bruxelles, Belgium C. Poleunis, Univ. catholique de Louvain, Belgium P. Laha, Vrije Univ. Brussel, Belgium P. Viville, Materia Nova, Belgium A. Delcorte, Univ. catholique de Louvain, Belgium P. Bertrand, Univ. catholique de Louvain, Belgium H.A. Terryn, Vrije Univ. Brussel, Belgium R. Lazzaroni, Materia Nova, Belgium F.A.B. Reniers, Univ. Libre de Bruxelles, Belgium |
| Correspondent: | Click to Email |
The exceptionally low surface energy of polytetrafluoroethylene (PTFE), due to the CF2 functional groups present on its surface gives the polymer advantageous properties such as hydrophobicity. In order to create PTFE-like films, low pressure plasma deposition of fluorocarbon films has been extensively studied in the last decade. These works focus however on the use of gaseous precursors such as CF4, C2F6 or C4F8.
In the present study, hydrophobic fluorocarbon coatings have been synthesized from two different precursors, which are liquid at room temperature. Perfluorohexane (C6F14), a fully saturated monomer and perfluoro(2-methylpent-2-ene) (C6F12) containing one unsaturated bond are injected in a dielectric barrier discharge (DBD) by a continuous argon or helium flow. In order to characterize the plasma polymer films and the texturization process, both, analysis of the surface and the gas phase have been performed.
Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) measurements have been performed to highlight the structure and composition of the CxFy films depending on the Yasuda factor (W/FM), throughout the influence of the power and the monomer flow rate. Water contact angle (WCA) measurements have shown that the hydrophobicity properties of the fluorocarbon films were similar to that of PTFE as WCA of 110° have been obtained. However, the structure also depends on the nature of the carrier gas (argon or helium) and in some cases, WCA as high as 140° were achieved. Atomic force microscopy AFM measurements are used to correlate the increase in hydrophobicity with the increase in roughness, which could be linked to the film thickness.
In order to complete the analysis of the polymerization process, mass spectrometry (MS) and optical emission spectroscopy (OES) have been performed. Fluorocarbon compounds such as CF, CF2, CF3, or higher mass fragments such as C3F3 or C2F4 have clearly been identified. Their detection combined to the SIMS analysis could help us to understand the polymerization mechanism/reaction of the two precursors.