Chemical and physical effect of SiO2 and TiO2 nanoparticles on highly hydrophobic fluorocarbon hybrid coatings synthesized by atmospheric plasma

The impact of the presence of TiO2 and SiO2 nanoparticles on the properties of fluorocarbon films synthesized by atmospheric pressure plasma in argon and helium is investigated in this study. The hydrophobicity, chemical composition and roughness of the films are analyzed by Water Contact Angle (WCA), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and profilometry. As expected, a significant impact of the nanoparticles on the roughness and therefore on the hydrophobicity of the films is observed and so regardless their nature. However, we show that the impact of the nanoparticles is different whether He or Ar are use as plasmagen gas, as He doesn't induce a significant intrinsic roughness, whereas Ar does. We show that the presence of SiO2 nanoparticles underneath the deposited film has no influence on the chemical composition of the films whatever the deposition time, the plasma power and the carrier gas (helium or argon) are. On the contrary, the presence of TiO2 nanoparticles leads to the degradation of the coatings over time. The influence of the plasma power of the discharge and the deposition time is also discussed. Finally, superhydrophobic coatings are synthesized by increasing the concentration of nanoparticles underneath the deposited films.