A Monte Carlo study of phase separation processes in immiscible binary mixtures with a surfactant

Phase separation processes of an immiscible binary mixture, which contains amphiphilic molecules (surfactants) or impurity molecules, have been investigated by Monte Carlo (MC) simulations on a 2-dimensional square lattice. The scattering structure function is calculated, which shows a slowing down of the growth rate of its peak height as a function of the increasing surfactant or impurity concentrations. Such a slowing down has actually been observed in real experiments on polymer blends containing amphiphilic block copolymers. The excluded volume effects of surfactant molecules are discussed.