Geometry-dominated fluid adsorption on sculpted solid substrates

Abstract

The shape and chemical composition of solid surfaces can be controlled at a mesoscopic scale. Exposing such structured substrates to a gas that is close to coexistence with its liquid phase can produce quite distinct adsorption characteristics compared to those of planar systems, which may be important for technologies such as super-repellent surfaces or micro-fluidics. Recent studies have concentrated on the adsorption of liquids on rough and heterogeneous substrates, and the characterization of nanoscopic liquid films. But the fundamental effect of geometry on the adsorption of a fluid from the gas phase has hardly been addressed. Here we present a simple theoretical model which shows that varying the shape of the substrate can exert a profound influence on the adsorption isotherms of liquids. The model smoothly connects wetting and capillary condensation through a number of examples of fluid interfacial phenomena, and opens the possibility of tailoring the adsorption properties of solid substrates by sculpting their surface shape.

Classical density functional study of wetting transitions on nanopatterned surfaces

“…Wetting and interfacial phenomena are dominated by the rich interplay between intermolecular forces and the fluctuation effects associated with thermal noise and interfacial capillary waves [8][9][10][11][12]. These lead to a very rich picture of possible surface phase behaviour occurring over different length-scales, that call for cross-disciplinary fundamental investigations.…”

Motion of Nanodroplets near Edges and Wedges

“…Wetting phenomena [1,2] and thin film dynamics [3] on rough [4] or topographically structured [5,6] substrates have been studied in detail both experimentally [5,6,7,8] and theoretically [4,9,10]. To a large extent these investigations are motivated by the fact that generically substrates are rough, in particular those playing an important role in technological processes such as oil recovery, coating, lubrication, and paper processing.…”

Colloidal crystals and water: Perspectives on liquid–solid nanoscale phenomena in wet particulate media

“…While the assessment of multilayer adsorption at moderate humidities is still debated in planar systems, the situation becomes even more complex in convoluted surfaces [3,102,103] like those in particulate media. Water film thickness may increase on corrugated surfaces in a manner not attributable to capillary condensation at the asperities.…”