Symmetric and Asymmetric Meniscus Collapse in Wetting Transition on Submerged Structured Surfaces
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- 作者：Pengyu Lv ; Yahui Xue ; Hao Liu ; Yipeng Shi ; Peng Xi ; Hao Lin ; Huiling Duan
- 刊名：Langmuir
- 出版年：2015
- 出版时间：February 3, 2015
- 年：2015
- 卷：31
- 期：4
- 页码：1248-1254
- 全文大小：398K
- ISSN：1520-5827
文摘
The wetting transition from the Cassie鈥揃axter to the Wenzel state is a phenomenon critically pertinent to the functionality of microstructured superhydrophobic surfaces. This work focuses on the last stage of the transition, when the liquid鈥揼as interface touches the bottom of the microstructure, which is also known as the 鈥渃ollapse鈥?phenomenon. The process was examined in situ on a submerged surface patterned with cylindrical micropores using confocal microscopy. Both symmetric and asymmetric collapses were observed. The latter significantly shortens the progression of the metastable state prior to the collapse when compared with the former and hence may affect the lifespan of superhydrophobicity. Further experiments identified that asymmetric collapse were induced by impurities due to prior use of the structure. The problem is thus of broad relevance, since endurance through cycles is a practical requirement for these functional surfaces. Finally, the use of hierarchical structures is proposed as a remedy. The embedded self-cleaning mechanism serves to effectively remove the impurities, so as to avoid the triggering mechanism for asymmetric collapses.