Water Droplet Motion Control on Superhydrophobic Surfaces: Exploiting the Wenzel-to-Cassie Transition
Water Droplet Motion Control on Superhydrophobic Surfaces: Exploiting the Wenzel-to-Cassie Transition
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DOI：
10.1021/la104669k
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发表时间：
2011-03-15
期刊：
影响因子：
3.9
通讯作者：
Craig, Vincent S. J.
中科院分区：
文献类型：
--
作者：
Liu, Guangming;Fu, Lan;Craig, Vincent S. J.
已知粗糙疏水性表面上的水滴以两种状态存在;一种是液滴被刺穿在表面粗糙体上（Wenzel状态），另一种是超疏水状态，其中空气保持被困在液滴下方（Cassie状态）。在这里，我们证明了水滴可以从Wenzel到Cassie状态，即使前者是积极的青睐。我们发现，两个不同的超疏水状态产生。一个是真正的Cassie状态，而另一个表现出超疏水性，在没有被困在表面粗糙度的气相。此外，我们可以选择性地驱动倾斜的结构化疏水表面上的水滴的运动，通过利用Wenzel-to-Cassie转换。这可以通过加热基板或通过使用激光直接加热液滴来实现。
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.