Superhydrophobic states
Superhydrophobic states
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DOI：
10.1038/nmat924
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发表时间：
2003-07-01
期刊：
影响因子：
41.2
通讯作者：
Quéré, D
中科院分区：
文献类型：
--
作者：
Lafuma, A;Quéré, D
众所周知，疏水性固体的粗糙度增强了其疏水性。水在这种扁平固体上的接触角通常为100 °至120°的量级，但如果它们是粗糙的或显微织构的，则达到高达160 °至175°的值。这一结果是显著的，因为这种行为不能仅由表面化学产生。两个不同的假说被经典地提出来解释这种效应。一方面，粗糙度增加了固体的表面积，这在几何上增强了疏水性（Wenzel模型）。另一方面，空气可以保持被困在液滴下方，这也导致超疏水行为，因为液滴部分地位于空气上（Cassie模型）。然而，它在这里示出，这两种情况是非常不同的，从他们的粘合剂性能，因为文泽尔滴被发现是高度钉扎。此外，可以在Cassie和Wenzel状态之间诱导不可逆的转变，并且通常与超疏水性相关的抗粘附性的损失。
It is well known that the roughness of a hydrophobic solid enhances its hydrophobicity,,,,,,,,,. The contact angle of water on such flat solids is typically of the order of 100 to 120°, but reaches values as high as 160 to 175° if they are rough,,or microtextured,,,. This result is remarkable because such behaviour cannot be generated by surface chemistry alone. Two distinct hypotheses are classically proposed to explain this effect. On one hand, roughness increases the surface area of the solid, which geometrically enhances hydrophobicity (Wenzel model). On the other hand, air can remain trapped below the drop, which also leads to a superhydrophobic behaviour, because the drop sits partially on air (Cassie model). However, it is shown here that both situations are very different from their adhesive properties, because Wenzel drops are found to be highly pinned. In addition, irreversible transitions can be induced between Cassie and Wenzel states, with a loss of the anti-adhesive properties generally associated with superhydrophobicity.