Droplets on Slippery Lubricant-Infused Porous Surfaces: A Macroscale to Nanoscale Perspective

Abstract

A recent design approach in creating super-repellent surfaces through slippery surface lubrication offers tremendous liquid-shedding capabilities. Previous investigations have provided significant insights into droplet−lubricant interfacial behaviors that govern antiwetting properties but have often studied using macroscale droplets. Despite drastically different governing characteristics of ultrasmall droplets on slippery lubricated surfaces, little is known about the effects at the micro-and nanoscale. In this investigation, we impregnate a three-dimensionally, well-ordered porous metal architecture with a lubricant to confirm durable slippery surfaces. We then reduce the droplet size to a nanoliter range and experimentally compare the droplet behaviors at different length scales. By experimentally varying the lubricant thickness levels, we also reveal that the effect of lubricant wetting around ultrasmall droplets is intensely magnified, which significantly affects the transient droplet dynamics. Molecular dynamics computations further examine the ultrasmall droplets with varying lubricant levels or pore cut levels at the nanoscale. The combined experimental and computational work provides insights into droplet interfacial phenomena on slippery surfaces from a macroscale to nanoscale perspective.

Microdroplet self-propulsion during dropwise condensation on lubricant-infused surfaces

“…The oil meniscus surrounding a droplet becomes increasingly important as the droplet size decreases, as it plays a key role in droplet dynamics on LIS. 31 The wetting state of a millimetric droplet placed on LIS has been extensively studied. 17,19,20,23 As shown in Fig.…”

“…The oils will cloak condensed water droplets due to a positive spreading coefficient, S ow(a) = γwa -γoa -γow = 2.4 mN/m > 0. 16,17,21 Both Krytox oils and silicone-based vacuum pump oil are widely used in design of stable LISs in previous studies 24,31 and completely spread on the nanostructure-textured surfaces in the presence of both of air and water 19,32,33 , indicating the formation of a thin oil layer between water droplets and the substrate. Using 3D confocal fluorescence microscopy we confirm the presence of the thin film underneath the droplets (see Fig.…”

Life and death of liquid-infused surfaces: a review on the choice, analysis and fate of the infused liquid layer

“…59 Although droplets moving on LIS oleoplane, 80 energy is lost through viscous dissipation in the wetting ridge, 128 causing droplet motion to be dependent on the size of the droplet. 65…”

Depletion of Lubricant from Nanostructured Oil-Infused Surfaces by Pendant Condensate Droplets

“…45 A decrease in droplet mobility which can negatively affect thermal transport has also been reported. 24,49 Typical industrial processes that use condensers, however, should last for years. 50 As a result, SLIPS condensation is not widely adopted for industrial applications to date.…”