On the Kinetics of the Formation of Ionic Micelles II. Analysis of the Time Constants

In relaxation experiments on aqueous solutions of surfactants one observes two processes. Following the pioneer work of Aniansson and Wall, the fast process is attributed to the change of the mean aggregation number of the micelles, while the slower one is attributed to the change of the total number of micelles. In this paper, the analysis of the fast relaxation process is first clarified. Second, the slower of the two relaxation processes is reexamined. It is suggested that their assumption of negligible flux in the abundant region leads to unphysical behavior of the micelle distribution. An alternative treatment is given which leads to a different result. The concentration dependence of the time constant is then derived for ionic systems in which the role of the counter ions has to be considered. This new result for the slow relaxation process together with the original result for the fast relaxation process are compared with experiments on the ionic systems H2O — NaTS and H2O — TTABr. Since results for nonionic systems form a limiting case of the more general results, comparison with experiments on the nonionic Triton‐X‐100 is also made. Satisfactory agreements are obtained for both types of systems