期刊
ULTRAMICROSCOPY
卷 107, 期 10-11, 页码 969-979出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.ultramic.2007.04.011
关键词
surface phenomena; liquid-solid interfaces; wetting
类别
Superhydrophobic surfaces should have high contact angles (CA) with water and low contact angle hysteresis (CAH). High CA may be achieved by increasing surface roughness, while in order to have low CAH, superhydrophobic surfaces should be able to form a stable composite interface with air pockets between solid and liquid. Capillary waves, nanodroplets condensation, hydrophilic spots due to chemical surface inhomogeneity, and liquid pressure can destroy the composite interface. These destabilizing factors have different characteristic length scales, so a hierarchical roughness is required to resist them. It is shown that convex rather than concave profile enhances stability, so nanoscale convex bumps should be superimposed over microasperities, in order to pin the liquid-air interface. In addition, the nanoroughness is required to support nanodroplets. The ability of the interface to support high pressure requires high asperity density and size, so it is in conflict with the requirement of low fractional solid-liquid contact area for low CAH and slip length. The new parameter, spacing factor for asperities, is proposed, and requirements for optimum design, which combines conflicting conditions, are formulated and discussed. Remarkably, biological superhydrophobic surfaces satisfy these requirements. (c) 2007 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据