Water droplet motion control on superhydrophobic surfaces: Exploiting the Wenzel-to-Cassie transition

Date

2011

Authors

Liu, Guangming
Fu, Lan
Rode, Andrei V
Craig, Vincent

Journal Title

Journal ISSN

Volume Title

Publisher

American Chemical Society

Abstract

Water droplets on rough hydrophobic surfaces are known to exist in two states; one in which the droplet is impaled on the surface asperities (Wenzel state) and the other, a superhydrophobic state in which air remains trapped beneath the droplet (Cassie state). Here, we demonstrate that water droplets can transit from the Wenzel-to-Cassie state even though the former is energetically favored. We find that two distinct superhydrophobic states are produced. One is a true Cassie state, whereas the other exhibits superhydrophobicity in the absence of a vapor phase being trapped in the surface roughness. Furthermore, we can selectively drive the motion of water droplets on tilted structured hydrophobic surfaces by exploiting Wenzel-to-Cassie transitions. This can be achieved by heating the substrate or by directly heating the droplet using a laser.

Description

Keywords

Keywords: Cassie state; Hydrophobic surfaces; Rough hydrophobic surfaces; Super-hydrophobic surfaces; Superhydrophobic state; Superhydrophobicity; Surface asperities; Two-state; Vapor Phase; Water droplets; Wenzel state; Drops; Heating; Surface chemistry; Surface p

Citation

Source

Langmuir

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1021/la104669k

Restricted until

2037-12-31