COMPUTER-SIMULATIONS OF A WATER OIL INTERFACE IN THE PRESENCE OF MICELLES

AMPHIPHILIC molecules such as detergents or lipids, which contain a hydrophilic 'head' and a hydrophobic 'tail' are capable of forming a wide variety of complex structures, including micelles, vesicles, bilayers, monolayers and liquid crystalline structures. This property is essential in many biological processes and is exploited in industrial and domestic applications, but remains poorly understood at a molecular level. Here we present the results of computer simulations of a molecular model for an oil-water-surfactant system. Micelles form spontaneously in the water phase and a monolayer of surfactants forms at the oil/water interface. A depletion layer, containing only water, separates this monolayer from the micelles. The density profiles of the micelles and the water show pronounced oscillations, which result from packing constraints on the micelles near the interface. These oscillations in the water density profile furnish a possible explanation of the results of neutron reflectivity experiments on water-surfactant systems. © 1990 Nature Publishing Group.