Manipulating wetting and pore filling by wall transparency

Atomically thin walls become increasingly prevalent in modern technologies. Exhibiting a unique property—transparency to interparticle interactions—such walls influence processes as diverse as capacitive energy storage, electron transfer, and wetting. However, the impact of wall transparency on wetting and capillary phenomena remains poorly understood. Herein, we employ classical density functional theory to explore how van der Waals interactions across thin solid walls affect capillarity and substrate wetting. Our findings demonstrate that a fluid-filled, sidewise-open channel beneath a thin wall can drastically enhance the lyophobicity of the wall (hydrophobicity if fluid is water), up to the point of effectively transforming lyophilic surfaces into lyophobic ones. Conversely, a fluid covering a thin wall can convert capillary condensation to drying and induce unusual capillary phases within the channel. These findings highlight the potential of wall transparency as a tool for manipulating channel filling and wetting behaviors, emphasizing its significance for interfacial phenomena and fluid adsorption in porous materials.