A Monte Carlo study of the electrostatic interaction between highly charged aggregates. A test of the cell model applied to micellar systems

Abstract

Monte Carlo simulations of electrolyte solutions under conditions corresponding to ionic micellar solutions have been performed. The cell model usually applied in the electrostatic theories of micelles has been tested and found to be valid for thermodynamic properties only at low micelle concentrations. However, the counterion distribution close to the micellar surface is correctly described within the cell model even at high concentrations. No dramatic difference in the accuracy of the cell model approximation of mono‐ and divalent counterions was found. The micelle–micelle and ion–ion radial distribution functions obtained in the simulations show a considerably structure even at low concentrations. The different radial distribution functions and thermodynamic properties calculated in the simulations have been compared with the results found from solutions of the hypernetted chain equation. The conclusion is that the hypernetted chain equations is a less useful approximation in miceller systems as compared to the Poisson–Boltzmann approximation.