Nanodrop on a nanorough hydrophilic solid surface: Contact angle dependence on the size, arrangement, and composition of the pillars

被引:29
作者
Berim, Gersh O. [1 ]
Ruckenstein, Eli [1 ]
机构
[1] SUNY Buffalo, Dept Chem & Biol Engn, Buffalo, NY 14260 USA
关键词
Rough surface; Nanodrops; Density functional theory; Contact angle; TEXTURED-SURFACES; WATER; CASSIE; HYSTERESIS; WENZEL; LOTUS; DROPS;
D O I
10.1016/j.jcis.2011.03.037
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
A two-dimensional nanodrop on a hydrophilic solid surface decorated with nanopillars is examined using a nonlocal density functional theory. It is shown that, in contrast to the commonly used Wenzel formula, even an extremely small roughness can considerably increase the contact angle. The contact angle depends on the distance between pillars, their height and width, as well as their composition. It was found that for all selected pillar heights and compositions, the largest contact angle is obtained when the distance between pillars acquires a size at which the liquid molecules can no longer penetrate between them. The further decrease in the interpillar distance decreases the contact angle, in qualitative agreement with the Cassie-Baxter formula. Considering pillars of various compositions, the role of the gradient of the fluid-solid interaction potential is examined. The presence of such a gradient does not allow the formation of a stable nanodrop on the surface. However, asymmetrical metastable nanodrops can be formed. (c) 2011 Elsevier Inc. All rights reserved.
引用
收藏
页码:304 / 310
页数:7
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