| AVS 60th International Symposium and Exhibition | |
| Advanced Surface Engineering | Wednesday Sessions |
| Session SE+PS-WeA |
| Session: | Atmospheric Pressure Plasmas |
| Presenter: | F.A.B. Reniers, Université Libre de Bruxelles, Belgium |
| Correspondent: | Click to Email |
Atmospheric plasma present nowadays numerous applications in the treatment of surfaces. They can be used for the cleaning of metals, for the reduction of surface oxides, to increase the adhesion of polymers, to deposit a wide variety of coatings from anticorrosion ones to biocompatible ones, including hybrid multifunctional coatings. They also have an effect on the surface roughness. Although the principles of the main technologies used (dielectric barrier discharge, RF discharges,…) are well known, the mechanisms involved in the different processes are still partly to be determined. Through a few detailed examples, the talk will try to go deeper in the understanding of what is going on in the process. The current limitations of atmospheric plasma technologies (what can be done, and what cannot be done (yet)) will conclude the talk.
Some detailed examples :
- Understanding the mechanisms for etching PTFE by atmospheric plasma to make it superhydrophobic. Through a combined study of the gas phase and the polymer by optical emission spectrometry, dynamic water contact angle, AFM, XPS and weight measurements, we will evidence the selected effect of atomic oxygen, metastable helium and UV photons on the etching process. The etching study is extended to a range of other polymers, ranging from PE to PTFE, with an increasing number of fluorinated atoms. Different mechanisms are proposed.
- The deposition of atmospheric plasma coatings usually leads to coatings exhibiting a good adhesion to the substrate. This adhesion, evidenced by peeling test, can be studied at the molecular level. The case of poly-AMA coatings and Silane coatings on aluminum will be presented.
- Plasma polymerization is strongly influenced by the chemical reactivity of the precursor molecule. A wide selection of molecules of precursor molecules, liquid at room temperatures have been injected in dielectric barrier discharge (from pure CxHy, to CxCly and CxFy, and esters such as nPIB, nPMA, AMA). We will show the effect of the double bonds on the final chemical structure of a coating, and on the deposition rate. We will also show that double bonds known to be unreactive in conventional polymerization can easily be activated in plasma. The effect of halogenated atoms present on the precursor is also studied
Finally, some perspectives regarding the future applications of atmospheric plasma will be discussed. Geometrical aspects, frequency range, hybrid coatings, microtexturing, deposition rates, will be approached.