Evaporation in the presence of particles in a model porous medium: impact of corner liquid films

Abstract

Visualization experiments with a microfluidic channel network (micromodel) were performed to study evaporation in the presence of colloidal particles. Comparisons were then performed, changing the wetting properties of the micromodel thanks to a plasma treatment. It was found that the most hydrophilic micromodel led to a faster drying and a different final distribution of the deposited particles within the channel network compared to the less hydrophilic micromodel. This is explained by the impact of capillary liquid films forming in corners of the channels. The observations suggest that the liquid corner films form a better-connected sub-network in the case of the more hydrophilic network providing a pathway for the transport of particles. As indicated by the longer drying, the corner film subnetwork is less well-connected in the less hydrophilic network, which eventually leads to a quite different final particle deposit pattern.