The physics of surfactant dissolution

Abstract

We have examined the early stages of surfactant dissolution and mesophase formation using a dimer-solvent model with phase behaviour representative of surfactant-water systems. We use an orientational order parameter to characterize systematically the appearance of mesophases. We find the process is diffusion controlled, and the appearance of mesophases is governed adiabatically by the equilibrium phase diagram from the earliest point at which the orientational order parameter can reliably distinguish between mesophases, when only a few repeat spacings of the mesophase microstructures are present. In real systems, such a stage would correspond to times of the order of a few microseconds after the initial contact.