Properties of a ternary system with fixed oil and water components, but an amphiphile of varying strength, are calculated by means of a lattice model and the Landau-Ginzburg free energy it generates. Using the lattice model, we calculate the variation of the amphiphile concentration at the base and apex of the three-phase triangle from the tricritical to the four-phase point, as well as the oil-water interfacial tension and interfacial profiles. These profiles are combined with the Landau-Ginzburg free energy to determine, for the same range of amphiphiles, the bending moduli that describe the nature of the surfactant sheet separating oil and water within the microemulsion.

• Received 21 February 1992

DOI:https://doi.org/10.1103/PhysRevA.46.985