Electrostatic energies in an ionic micellar solution in the mean spherical approximation

We present a method for calculating electrostatic energies of an ionic micellar solution under the conditions of quasi-spherical micelles and point-like counterions. It is based on a multi-component mean spherical approximation (MMSA) theory with non-additive diameters. The partial structure factors can be evaluated analytically according to a method due to Khan and Ronis, and used to calculate the electrostatic energies. As an example, a micellar solution formed by Cesium Dodecyl Sulfate in water has been studied with small angle neutron scattering. The micellar size and effective charge are extracted from analysis of small angle neutron scattering data, and used to evaluate the internal energy and Gibbs free energy of the micellar solution.