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 language | Undefined |
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Pages (from-to) | 116102-1-116102-4 |
Number of pages | 4 |
Journal | Physical review letters |
Volume | 104 |
Issue number | 11 |
DOIs | |
Publication status | Published - 2010 |
Keywords
- IR-79182
- METIS-265509