Monte Carlo study of interfacial properties in an amphiphilic system

A three-component model representing a balanced, amphiphilic system at a three-phase coexistence of oil-, water-rich, and disordered phases is simulated, and interfacial tensions between all phases are obtained from histogram methods. We find that the disordered phase wets the oil-water interface, and that its tension is reduced due to the presence of the amphiphile by a factor of 93. The determination of the structure function shows that the system is between disorder and Lifshitz lines. These three factors are all consistent with the simulated amphiphile being weak. Fluctuations do not reduce the tension significantly from mean-field estimates, but do alter the location of the wetting transition. The latter is in accord with the expected behavior of a system in which the interfacial tension is small.