Wetting and drying on gradient-nanostructured C:F surfaces synthesized using a gas aggregation source of nanoparticles combined with magnetron sputtering of polytetrafluoroethylene

The impact of surface roughness on wettability and droplet drying dynamics was investigated on coatings with a spatially homogeneous chemical composition, but with a gradient in their roughness. Such coatings were prepared by a simple vacuum-based technique that utilizes a combination of a gas aggregation source of Ag nanoparticles and the radio-frequency magnetron sputtering of hydrophobic polytetrafluoroethylene. It was demonstrated that the roughness influenced not only the static water contact angle that monotonously increases with increasing roughness, but also had a strong impact on the water contact hysteresis, as well as on the dynamics of droplet drying.