Hydrophobicity of ion-plated PTFE coatings

The influence of roughness on the wetting properties of ion-plated poly(tetrafluroethylene) (PTFE) coatings has been investigated using atomic force microscopy (AFM) and contact angle goniometry techniques. PTFE coatings with different surface roughness have been obtained by applying different substrate bias DC voltages during ion plating. Surface roughness has been characterized from the surface morphology studies carried out using atomic force microscopy. It was found that the majority of surface asperities for rough coatings prepared in this study have dimensions of a few nanometers, 6-13 nm. For such coatings, high water contact angles, 150-160 degrees, were observed. Importantly, the measured contact angles correlated with surface texture (roughness) as determined by AFM. These measurements provide additional proof on the effect of nanometer-size surface asperities on the wetting characteristics of hydrophobic coatings. Published by Elsevier Science S.A.