Relation of the Equilibrium Contact Angle to Liquid and Solid Constitution
01 Jan 1964-pp 1-51
About: The article was published on 1964-01-01 and is currently open access. It has received 1614 citations till now. The article focuses on the topics: Contact angle.
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TL;DR: In this paper, a flat fluid interface moving steadily over a flat solid is modeled with the creeping flow approximation, which turns out to be self-consistent, and the role of long-range forces are explored with the aid of the lubrication flow approximation.
1,419 citations
TL;DR: Water repellency (hydrophobicity) of soils is a property with major repercussions for plant growth, surface and subsurface hydrology, and for soil erosion as discussed by the authors.
1,415 citations
TL;DR: It is found that solvent properties of water within the interphase separating a solid surface from bulk water solution vary with contacting surface chemistry, and this interphase can extend tens of nanometers from a water-contacting surface due to a propagation of differences in self association between vicinal water and bulk-phase water.
1,396 citations
TL;DR: Future directions and opportunities for surface scientists working in biomedical research include exploiting biological knowledge, biomimetics, precision immobilization, self-assembly, nanofabrication, smart surfaces, and control of non-specific reactions.
1,283 citations
TL;DR: Four design parameters are proposed that predict the measured contact angles for a liquid droplet on a textured surface, as well as the robustness of the composite interface, based on the properties of the solid surface and the contacting liquid, that allow two different families of re-entrant surfaces to be produced.
Abstract: Superhydrophobic surfaces display water contact angles greater than 150° in conjunction with low contact angle hysteresis. Microscopic pockets of air trapped beneath the water droplets placed on these surfaces lead to a composite solid-liquid-air interface in thermodynamic equilibrium. Previous experimental and theoretical studies suggest that it may not be possible to form similar fully-equilibrated, composite interfaces with drops of liquids, such as alkanes or alcohols, that possess significantly lower surface tension than water (γlv = 72.1 mN/m). In this work we develop surfaces possessing re-entrant texture that can support strongly metastable composite solid-liquid-air interfaces, even with very low surface tension liquids such as pentane (γlv = 15.7 mN/m). Furthermore, we propose four design parameters that predict the measured contact angles for a liquid droplet on a textured surface, as well as the robustness of the composite interface, based on the properties of the solid surface and the contacting liquid. These design parameters allow us to produce two different families of re-entrant surfaces— randomly-deposited electrospun fiber mats and precisely fabricated microhoodoo surfaces—that can each support a robust composite interface with essentially any liquid. These omniphobic surfaces display contact angles greater than 150° and low contact angle hysteresis with both polar and nonpolar liquids possessing a wide range of surface tensions.
1,132 citations