Evaporation of droplets on superhydrophobic surfaces: Surface roughness and small droplet size effects

Xuemei Chen, Ruiyuan Ma, Jintao Li, Chonglei Hao, Wei Guo, B. L. Luk, Shuai Cheng Li, Shuhuai Yao, Zuankai Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

204 Citations (Scopus)

Abstract

Evaporation of a sessile droplet is a complex, nonequilibrium phenomenon. Although evaporating droplets upon superhydrophobic surfaces have been known to exhibit distinctive evaporation modes such as a constant contact line (CCL), a constant contact angle (CCA), or both, our fundamental understanding of the effects of surface roughness on the wetting transition remains elusive. We show that the onset time for the CCL-CCA transition and the critical base size at the Cassie-Wenzel transition exhibit remarkable dependence on the surface roughness. Through global interfacial energy analysis we reveal that, when the size of the evaporating droplet becomes comparable to the surface roughness, the line tension at the triple line becomes important in the prediction of the critical base size. Last, we show that both the CCL evaporation mode and the Cassie-Wenzel transition can be effectively inhibited by engineering a surface with hierarchical roughness.

Original languageEnglish
Article number116101
JournalPhysical Review Letters
Volume109
Issue number11
DOIs
Publication statusPublished - 10 Sept 2012
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy

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