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.
Original language | English |
---|---|
Pages (from-to) | 2595-2600 |
Number of pages | 6 |
Journal | Langmuir |
Volume | 27 |
Issue number | 6 |
DOIs | |
Publication status | Published - 15 Mar 2011 |