Cross-over between first-order and critical wetting at the liquid-vapour interface of n-alkane/methanol mixtures: tricritical wetting and critical prewetting

A. I. Posazhennikova; J. O. Indekeu; D. Ross; D. Bonn; J. Meunier

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arXiv · cond-mat/0111206

Cross-over between first-order and critical wetting at the liquid-vapour interface of n-alkane/methanol mixtures: tricritical wetting and critical prewetting

A. I. Posazhennikova·J. O. Indekeu·D. Ross·D. Bonn·J. Meunier

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Abstract

A mean-field theory is presented which describes the basic observations of recent experiments revealing rich wetting behaviour of n-alkane/methanol mixtures at the liquid-vapour interface. The theory, qualitative and in part heuristic, is based on a microscopic lattice-gas model from which a Cahn-Landau approach is distilled. Besides the physics associated with the short-range components of the intermolecular interactions, effects of the long-range tails of the net van der Waals forces between interfaces are also taken into account. Including weak long-range forces which favour wetting in the theory does not visibly alter the critical wetting transition for the nonane/methanol mixture, in contrast with the generic expectation of first-order wetting for such systems, but in good agreement with experiment. For decane/methanol weak long-range forces bring the transition very close to the prewetting critical point, leading to an adsorption behaviour closely reminiscent of short-range tricritical wetting, observed experimentally for alkane chain length between 9.6 and 10. Finally, for undecane/methanol the transition is clearly of first order. First-order wetting is also seen in the experiment.

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A. I. Posazhennikova, J. O. Indekeu, D. Ross, D. Bonn, J. Meunier. 2002-09-18. Cross-over between first-order and critical wetting at the liquid-vapour interface of n-alkane/methanol mixtures: tricritical wetting and critical prewetting. https://arxiv.org/abs/cond-mat/0111206

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