Freeze Fracture Approach to Directly Visualize Wetting Transitions on Nanopatterned Superhydrophobic Silicon Surfaces: More than a Proof of Principle

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• 作者：Stefan Wiedemann ; Alfred Plettl ; Paul Walther ; Paul Ziemann
• 刊名：Langmuir
• 出版年：2013
• 出版时间：January 22, 2013
• 年：2013
• 卷：29
• 期：3
• 页码：913-919
• 全文大小：384K
• 年卷期：v.29,no.3(January 22, 2013)
• ISSN：1520-5827

文摘

Freeze fracturing is applied to make the wetting behavior of artificially nanopatterned Si surfaces directly visible. For this purpose, almost hexagonally arranged nanopillars of fixed areal density (127 渭m^鈥?) and diameters (35 nm) but varying heights (40鈥?50 nm) were fabricated on silicon. Measurement of contact angles (CAs) including hysteresis allowed to distinguish between the Wenzel (W) and the Cassie鈥揃axter (CB) states with droplets completely wetting the pillars or residing on top of them, respectively. Providing additional depth contrast by evaporating the ice replica with thin carbon and (typically 3 nm) platinum layers under 45掳 allowed resolving 3D features of 5 nm within the ice replica. In this way, laterally sharp transitions from CB- to W-states could be revealed, indicating the formation of zero-curvature water surfaces even on the nanoscale.