Molecular dynamics study of the aqueous core of a reversed ionic micelle

The molecular structure and dynamics of a molecular electric double layer have been examined with the molecular dynamics simulation technique. A 50 ps trajectory from a simulation of a model system comprising 50 sodium ions and 1000 water molecules, spherically enclosed by a hydrophobic interface carrying 50 carboxylate groups, has been analyzed. The results show that the water structure is strongly distorted by the strong local fields and that the hydrophobic interface plays only a secondary role. The orientational polarization of the interfacial water molecules has been examined and compared with dielectric continuum theory. The dynamical results of this study show a reduced rate of translational as well as rotational motions of ionic hydrating water by a factor of 2–4 as compared to bulk water.