Self-organized structures in thin liquid films on chemically heterogeneous substrates: Effect of antagonistic short and long range interactions

Zope, Manoj ; Kargupta, Kajari ; Sharma, Ashutosh (2001) Self-organized structures in thin liquid films on chemically heterogeneous substrates: Effect of antagonistic short and long range interactions The Journal of Chemical Physics, 114 (16). 7211_1-7211_11. ISSN 0021-9606

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Official URL: http://jcp.aip.org/resource/1/jcpsa6/v114/i16/p721...

Related URL: http://dx.doi.org/10.1063/1.1359737

Abstract

Surface instability, dynamics, and morphology in spontaneous dewetting of a thin liquid film on a chemically heterogeneous substrate are studied based on nonlinear simulations for a system subjected to a long range van der Waals attraction and soft short-range repulsion. Characteristics of dewetting by a heterogeneity are clearly contrasted with the spinodal dewetting on a homogeneous surface. In the presence of a chemical heterogeneity, the instability is engendered by the gradient of intermolecular interactions that lead to a microscale wettability contrast. The time scale of instability can be substantially less than the spinodal time scale, especially for thinner films close to the critical thickness, and it varies inversely with the potential difference induced by the heterogeneity. Heterogeneity, on a very small length scale, can even destabilize a spinodally stable film. A local ordering of the structure (droplets and holes) around the heterogeneity produces "castle-moat," "ripples," and "flower" like morphologies, which are not predicted by the spinodal mechanism. A local enhancement of the long-range attraction on the patch leads to a longer ranged ordering of holes around the heterogeneous patch for relatively thicker films. In contrast, a decrease in the short-range repulsion on the heterogeneous patch encourages an even longer-ranged ordering of droplets for the thinner films.

Item Type:Article
Source:Copyright of this article belongs to American Institute of Physics.
Keywords:Liquid Films; Wetting
ID Code:46938
Deposited On:06 Jul 2011 10:52
Last Modified:06 Jul 2011 10:52

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