What makes AOT reverse micelles spherical?

It is known that sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles are spherical over a wide range of water-to-surfactant molar ratios. This contradicts the traditional concept of preferred curvature. In actual fact, this concept does not apply to the AOT monolayer because its free energy is almost a linear function of the mean curvature. To correctly predict the shape of AOT reverse micelles, it is necessary to take into account not only the curvature free energy but also the disjoining pressure arising primarily from the overlapping of the electrical double layers at the opposite sides of the water core. Based on these considerations, we develop a model to calculate the free energy of AOT reverse microemulsion. This model allows us to explain the sphericity and to calculate various thermodynamic properties: the enthalpy of solubilization, chemical potentials, polydispersity, and the phase diagrams. All results are in qualitative agreement with the available experimental data.