Collapse and Reversibility of the Superhydrophobic State on Nanotextured Surfaces
Collapse and Reversibility of the Superhydrophobic State on Nanotextured Surfaces
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DOI：
10.1103/physrevlett.112.216101
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发表时间：
2014-05-29
影响因子：
8.6
通讯作者：
Dietrich, Siegfried
中科院分区：
文献类型：
--
作者：
Checco, Antonio;Ocko, Benjamin M.;Dietrich, Siegfried
超疏水涂层通过将空气捕获在微观表面纹理内来排斥液体。然而，所得到的复合材料界面在外部压力下易于塌陷。由于纳米级的几何形状和限制效应，纳米尺寸的纹理应有助于更有弹性的涂层。在这里，我们使用原位X射线衍射研究的崩溃的超疏水状态的阵列中的约20 nm宽的硅纹理与圆柱形，圆锥形，和线性功能定义的嵌段共聚物自组装和等离子体蚀刻。我们发现，超疏水状态消失的临界压力以上，这取决于纹理的形状和大小。这种现象是不可逆的，但所有的圆锥形表面纹理表现出自发的，部分再现的捕获的气相液体减压后。该过程受气液交换动力学的影响。
Superhydrophobic coatings repel liquids by trapping air inside microscopic surface textures. However, the resulting composite interface is prone to collapse under external pressure. Nanometer-size textures should facilitate more resilient coatings owing to geometry and confinement effects at the nanoscale. Here, we use in situ x-ray diffraction to study the collapse of the superhydrophobic state in arrays of approximate to 20 nm-wide silicon textures with cylindrical, conical, and linear features defined by block-copolymer self-assembly and plasma etching. We reveal that the superhydrophobic state vanishes above critical pressures which depend on texture shape and size. This phenomenon is irreversible for all but the conical surface textures which exhibit a spontaneous, partial reappearance of the trapped gas phase upon liquid depressurization. This process is influenced by the kinetics of gas-liquid exchange.