Charge variance of ionic micelles: a significant parameter to account for and to predict changes in degrees of micelle ionization and in aggregation numbers.
In the context of the thermodynamics of self-assembling systems, which predicts that both the number-average number of aggregation, N(n), of the ionic surfactants and the number-average degree of ionic dissociation of the micelles, alpha(n), depend on the concentrations of micellized surfactant and counterion in the bulk, it is shown that a key parameter is the ratio between sigma(Q), the standard deviation of the micelle charge distribution of the micelles, and sigma(N), that of the aggregation numbers. In the case of hexadecyltrimethylammonium acetate-acetic acid (1:1) solutions, this ratio is calculated as ca. 0.1 from conductivity and aggregation number data.
Toullec
Jean
J
Laboratoire S.I.R.C.O.B. (C.N.R.S., UMR 8086), Université de Versailles, 45 Avenue des Etats-Unis, 78035 Cedex, Versailles, France. toullec@chimie.uvsq.fr