Title: Wetting transitions at fluid-fluid interfaces
Abstract: In certain binary liquid mixtures the liquid phase with the larger mass density forms a wetting layer which intrudes between the less dense liquid and the vapour. Using a model free energy functional we have calculated the density profiles and the thickness, t, of the wetting layer for several model binary mixtures. The variation of t with the height L spanned by the less dense liquid phase depends on the form chosen to model the attractive part of the intermolecular potentials. For inverse sixth power law potentials we find that, for L ⩽ 1>0-1 m, t varies approximately as L -1/3. Such behaviour was predicted by de Gennes and was found in ellipsometric experiments by Kwon et al. The calculated thicknesses, which lie between 30 and 160 Å, are similar to those which are measured. For exponentially decaying model potentials t varies approximately as L -0·13. Our results for a model which exhibits a first order wetting transition show that, for temperatures just above the wetting transition temperature, the thickness t will change discontinuously at a certain value of L. This behaviour, which has not yet been observed experimentally, is a manifestation of the thick-thin film transition of Cahn or, as it is sometimes called, prewetting.
Publication Year: 1983
Publication Date: 1983-06-10
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 33
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