Control of Liquids by Surface Energies
Our every day experience of handling liquids is strongly linked to the presence of gravity. In a zero gravity environment, as realized during parabola flights or in space crafts, it is almost impossible to pour water from a bottle into a glass. A close look at a glass of water already reveals the influence of interfacial energies: the curvature of the water meniscus bends up close to its rim due to the high wettability of clean glass surfaces by water. When compartmentalized into structures smaller than a characteristic length being typically on the order of 1 mm gravity becomes irrelevant and interfacial energies dominate both the statics and dynamics of a liquid down to a length scale of about 10 nm .
The strong impact of interfacial energies on the morphology of submillimeter- sized wetting droplets can be utilized to control the position and the shape of tiny amounts of liquid on specifically designed substrates.
KeywordsContact Angle Contact Line Laplace Pressure Vapor Interface Apparent Contact Angle
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