Robust liquid-infused surfaces through patterned wettability

Abstract

Liquid-infused surfaces display advantageous properties that are normally associated with conventional gas-cushioned superhydrophobic surfaces. However, the surfaces can lose their novel properties if the infused liquid drains from the surface. We explore how drainage due to gravity or due to an external flow can be prevented through the use of chemical patterning. A small area of the overall surface is chemically treated to be preferentially wetted by the external fluid rather than the infused liquid. These sacrificial regions disrupt the continuity of the infused liquid, thereby preventing the liquid from draining from the texture. If the regions are patterned with the correct periodicity, drainage can be prevented entirely. The chemical patterns are created using spray-coating or deep-UV exposure, two facile techniques that are scalable to generate large-scale failure-resistant surfaces.

A moving contact line as a rheometer for nanometric interfacial layers

“…PDMS can also be adsorbed to glass and metallic surfaces36. We anticipate that tailoring the polymer–liquid pair by appropriate choice of polymer, by functionalization of the end-groups, or by imbibition with a good solvent that is immiscible with the partially wetting liquid3738, will enable generalizing this method of eliminating contact angle hysteresis.…”

Controlled liquid entrapment over patterned sidewalls in confined geometries

“…However, there are several geometrical systems that are periodic in two directions [12][13][14][15][16][17][18][19]. The challenge in extending our approach to such systems arises from the effect of wetting dynamics since the interface can now progress in two directions and interface speed is required to predict relative movement between the two directions.…”

“…Such isolation of aqueous environment is achieved by introducing an artificial defect on the surface such as an obstacle or a depression [7][8][9][10][11]. Similarly, extensive research on liquid-infused surfaces demonstrates that a trapped liquid layer over a patterned surface lends remarkable surface properties [12][13][14][15][16][17][18][19]. Thus depending on the application, it may be desirable to either remove or trap a liquid layer over a surface.…”

“…There have been a series of studies on liquid-infused surfaces with geometric features on the order ∼10 μm where the authors show how the preexisting layer of oil in a groove (a model for a liquid-infused surface) can be drained by injecting water [16][17][18][19]. They also examined the effect of aspect ratio of the groove, presence of obstacles, viscosity ratio of the two phases, and presence of surfactant in the aqueous phase on the oil drainage.…”

Drop mobility on chemically heterogeneous and lubricant-impregnated surfaces

“…It shows that a higher shear stress or external pressure gradient results in lower lubricant retention and, for a given external fluid and a fixed shear stress, the less viscous lubricants achieve higher retention. A method to prevent drainage from textured surfaces consists in creating sacrificial regions with differing chemistry or using a lower lubricant viscosity [95].…”