Evaporation-Triggered Wetting Transition for Water Droplets upon Hydrophobic Microstructures

Peichun Amy Tsai, Rob G.H. Lammertink, Matthias Wessling, Detlef Lohse

Research output: Contribution to journalArticleAcademicpeer-review

144 Citations (Scopus)
94 Downloads (Pure)

Abstract

When placed on rough hydrophobic surfaces, water droplets of diameter larger than a few millimeters can easily form pearls, as they are in the Cassie-Baxter state with air pockets trapped underneath the droplet. Intriguingly, a natural evaporating process can drive such a Fakir drop into a completely wetting (Wenzel) state. Our microscopic observations with simultaneous side and bottom views of evaporating droplets upon transparent hydrophobic microstructures elucidate the water-filling dynamics and suggest the mechanism of this evaporation-triggered transition. For the present material the wetting transition occurs when the water droplet size decreases to a few hundreds of micrometers in radius. We present a general global energy argument which estimates the interfacial energies depending on the drop size and can account for the critical radius for the transition
Original languageUndefined
Pages (from-to)116102-1-116102-4
Number of pages4
JournalPhysical review letters
Volume104
Issue number11
DOIs
Publication statusPublished - 2010

Keywords

  • IR-79182
  • METIS-265509

Cite this