| Wed February 26th 2014 16:00 ZH286 | Seminar | Noncoalescence of sessile drops from miscible liquids Stefan Karpitschka |
Details:Liquid drops that are sitting on a solid support are well known to merge once they contact each other: capillary forces arising from the liquid-gas interfacial energy drive the system toward a state of minimal surface area. Quite unexpected, this behavior may totally change if the drops contain different though completely miscible liquids: instead of merging, the main drop bodies may remain separated, connected only through a thin liquid film. Such "noncoalescing" drops remain in this state for up to minutes and travel across their support. The origin is the Marangoni-effect: different liquids have different surface energies, and a flow from one drop to the other is induced. I"ll present experiments on the state of noncoalescence and an analytical description in the framework of lubrication theory. In addition, I"ll present experiments on the threshold between immediate (usual) coalescence and noncoalescence, which is sharp within the experimental resolution and described by a power law between contact angles and surface tension contrast. | ||
