Regensburg 2025 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 14: Wetting, Fluidics and Liquids at Interfaces and Surfaces II (joint session CPP/DY)

CPP 14.1: Talk

Monday, March 17, 2025, 17:30–17:45, H34

Vapor-mediated wetting and imbibition control on micropatterned surfaces — •Ze Xu and Stefan Karpitschka — Fachbereich Physik, Universität Konstanz, Konstanz, Germany

Wetting and evaporation of droplets on micropatterned surfaces are ubiquitous in nature and key to many technological applications, such as water/ice-proof coatings, spray cooling, inkjet printing, and semiconductor surface processing. The wettability of micropatterned surfaces is governed by surface chemistry and topography, and significant effort has been devoted to overcoming this intrinsic behavior, e.g. to dry or coat structures surfaces, by use of external stimuli like electromagnetic fields. However, these methods usually require specific materials, thus limiting their practical use. Here, we show that the spreading behavior of water droplets on hydrophilic surface patterns can be controlled and even temporarily inhibited by the presence of the vapor of a low surface tension liquid. We show that this delayed wicking arises from Marangoni forces due to vapor condensation at the droplet periphery that compete with the capillary wicking force of the surface topography. We further demonstrate how modulating the vapor concentration in space and time can be used to guide droplets across patterns and even extract liquid from fully imbibed films, devising new strategies for coating, cleaning and drying of functional surface designs.

Keywords: wetting; evaporation; Marangoni flows; patterned surfaces; liquid manipulation