Density-functional studies of amphiphilic binary mixtures. I. Phase behavior

Density-functional theory with interaction site model is applied to study binary mixtures consisting of Lennard-Jones atoms with hard-spherical cores (monomers) and bonded Lennard-Jones atoms of two hard-sphere sites (dimers). Strong amphiphilic interaction is shown to result in lamellae in the bulk condensed phase. A phase diagram showing disorder-lamellar phase boundaries and tricritical points is presented for a system with reduced interaction between the molecular species. Density distributions in the lamellar phase indicate that the mole fraction in the lamellae is determined by the concentration of the monomers. (C) 2000 American Institute of Physics. [S0021-9606(00)51034-4].