LAYERING, DEWETTING, AND FIRST-ORDER WETTING IN TERNARY AMPHIPHILIC SYSTEMS

A Ginzburg-Landau theory with a single scalar order parameter is used to study the wetting behavior in ternary mixtures of oil, water, and amphiphile. In particular, interfacial tensions and the contact angle of the middle phase between oil-rich and water-rich phases are examined, when the system approaches a Lifshitz critical point or an ordinary critical point. We find a variety of unexpected phenomena near these points, such as layering transitions and an extremely nonmonotonic behavior of the contact angle. Our results can be understood with the help of an effective interface potential for the oil/water interface, which we calculate exactly as a function of the width / of the middle phase. © 1995 American Institute of Physics.