Effective interface Hamiltonians for unbinding transitions in ternary amphiphilic mixtures

We outline an analytic method for deriving effective interfacial models, suitable for describing unbinding behaviour in ternary amphiphilic mixtures, from underlying non-critical bulk models. Herein we concentrate on deriving interfacial properties (the surface tension and rigidity coefficients) for the simple case of a free oil-phase/microemulsion interface. This calculation allows us to explicitly demonstrate the difference between the interfacial tension, which is a uniquely defined quantity, and the rigidities which are highly sensitive to the choice of interface location definition. clude by describing how the model derivation may be extended to include the effect of an external surface, which is appropriate for the study of wetting in a confined ternary mixture. We briefly summarize the results of a recent study of wetting at such a surface for which a rich phase diagram is predicted.