Hexadecane and water droplets impacting on amphiphobic surfaces

F. Veronesi, M. Raimondo, G. Guarini, G. Boveri
Institute of Science and Technology for Ceramics ISTEC CNR,

Keywords: amphiphobicity, hybrid coatings, drop impact, We number


The control of surface wetting and the ability to actively modulate its response in different environments and against different liquids can make a bulk material a new functional one. In the field of materials science, the impact of drops onto dry solid surfaces is a key phenomenon in many industrial applications, whose control - through a deep comprehension of the physico-chemical interactions at surface level - can lead to relevant innovation. In this work, examples of amphiphobic metals, alloys, glasses and ceramic are presented. Solid-liquid-air and liquid-liquid-air working interfaces have been realized by deposition of hybrid layers coupled, eventually, with a lubricant layer. Contact angles (CA) with water as high as 178°, CA Hysteresis (CAH) lower than 5° and CA with hexadecane up to 130° were achieved. A full characterization of surfaces was undertaken by XPS analyses and FESEM observations, while the impact and rebound behavior of both water and hexadecane drops was assessed at different impact speeds and We numbers using a high-speed camera. The main objective was to correlate the drop impact outcomes with the surface wettability, taking into account different parameters for both the liquid drop (impact velocity, surface tension) and the solid surface (morphology and chemistry).