Passive Removal of Highly Wetting Liquids and Ice on Quasi-Liquid Surfaces

Abstract

Surfaces with ultralow adhesion to liquids and solids have attracted broad interests in both fundamental studies and engineering applications from passive removal of highly wetting liquids and water harvesting to anti-/de-icing. The current state-of-the-art superomniphobic surfaces (rely on air lubricant) and liquid-infused surfaces (rely on liquid lubricant) suffer from severe issues for liquid repellency and ice removal: air/liquid lubricant loss or topography damage. Here, we create a durable quasi-liquid surface by tethering flexible polymer on various solid substrates. The untethered end of the polymer has mobile chains that behave like a liquid layer and greatly reduce the interfacial adhesion between the surface and foreign liquids/solids. Such a quasi-liquid surface with a 30.1 nm flexible polymer layer shows ultralow contact angle hysteresis (≤1.0°) to liquids regardless of their surface tensions. The highly wetting perfluorinated liquids like FC72 and Krytox101, as well as complex fluids like urine and crude oil, can be repelled from the surface. Moreover, wind can remove accreted ice from the surface in harsh conditions due to the negligible ice adhesion. We have demonstrated that the quasi-liquid surface shows robust performances in repelling highly wetting liquids, harvesting water, and removing ice, respectively.

Gradient Quasi‐Liquid Surface Enabled Self‐Propulsion of Highly Wetting Liquids

“…A uniform quasi‐liquid surface (UQLS) without a molecular gradient was used as a comparative surface. [ 41 ] All the surfaces were horizontally placed during the tests. Figure 3B illustrates the dynamic droplet growth and self‐propulsion mechanism on GQLS.…”

Dynamic Anti‐Icing Surfaces (DAIS)

“…The state-of-the-art liquid-like surfaces, for example, the slippery omniphobic covalently attached liquid surfaces, still exhibited limited thickness of QLL, which restricted sustainable ice removal. [111][112][113] Recently, a nonsticky and extremely flexible quasi-liquid surface (QLS) with a coating thickness of 30.1 nm was reported (Figure 8a), [114] which enabled extreme flexibility and quasi-liquid thickness of the surface. The QLS had omniphobic nature of exceptional repellency to water and organic The ice cube directly sitting on the silicon surface, ice cube with a sandwiched water layer on the silicon surface, ice cube on graphene, and ice cube with sandwiched water on graphene were named as IS, IaS, IG, and IaG, respectively.…”

“…The thickness of interfacial aqueous lubricant layers introduced above was generally in nanoscale, varying from a few molecules to tens of nanometer. [ 105 , 114 ] Aqueous layer with such thickness range led to ice adhesion strength of ≈26 kPa, which was good but still beyond the requirement for practical anti‐icing application (lower than ≈10 kPa). [ 14 , 25 , 26 ] To further increase the lubricant effects by interfacial aqueous lubricant layer, DAIS that could melt the interfacial ice and create thicker aqueous layer were developed.…”

“…a)The liquid repellency and ice removal property of the quasi-liquid surface (QLS). Adapted with permission [114]. Copyright 2020, American Chemical Society.…”

Near Field Condensation

“…To decrease shedding droplet size, enormous effort has been spent on tuning condensatesurface interactions via the use of hydrophobic 10,11 , superhydrophobic [12][13][14] , hybrid [15][16][17][18] , and slippery surfaces [19][20][21][22][23][24][25] . These approaches promote shedding with an increased population of small (~ 10 µm) droplets [19][20][21][22][23][24][25] . In spite of the success of developed laboratory-scale functional surfaces, lack of durability is the primary barrier to dropwise condensation application 28 .…”