Dewetting of a Liquid Film
If we record how a droplet spreads into a film and play it backwards, do we see the same as a video of a liquid film dewetting into a single droplet? Is it a video in reverse?
Our experiments use liquid dielectrophoresis to induce a droplet into an initial static film state on a surface which would not normally allow the liquid to form the film. When the voltage is removed (quenched), the droplet then re-gathers (dewets) into a single macroscopic droplet. The dewetting process has an initial stage where a dimple forms and the rim retracts, followed by a second stage which is a spherical cap droplet approaching its equilibrium shape. This starkly contrasts with the spreading of small a droplet into a film which follows a smooth sequence of spherical cap shapes. Dewetting is not a video in reverse of wetting.
Dewetting is an important consideration in the process of screen printing. A good description of this problem is given by Professor Steven Abbott.
Not spreading in reverse: The dewetting of a liquid film into a single drop A.M.J. Edwards, R. Ledesma-Aguilar, M.I. Newton, C.V. Brown and G. McHale, Science Advances 2 (2016) e1600183.
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