Some Thoughts Regarding Theoretical Aspects of the Corrin-Harkins Relation and the Micellization Product of Ionic Micelles

The dependence of the stability of ionic micelles on the ionic strength of the medium is examined analytically without recourse to any explicit expression of the surface potential of micelles. The present study is based on the idea developed by Evans, Mitchell, and Ninham (D. F. Evans, D. J. Mitchell, and B. W. Ninham, J. Phys. Chem. 88, 6344 (1984)) that the interfacial free energy at the water/hydrocarbon core interface is independent of the ionic strength of the medium. The Corrin-Harkins (C-H) relation, a linear relation between the logarithm of the critical micelle concentration (cmc) and the logarithm of the counterion concentration n(C), is obtained in the range of n(C) where the salting-out effect is negligible, under the condition that the area per monomer on the micelle surface decreases very weakly with n(C). The "micellization product" of the charged pseudophase model of ionic micelles is discussed. The linear dependence of the surface potential of ionic micelles on n(C) is derived while a part of the effects of salt on the micelle size/shape is allowed. Copyright 2001 Academic Press.