Dependence of Critical Micellar Concentrations on Intensive Variables

An analysis of the relations between critical micellar concentrations and temperature, or pressure, indicates that experimental data fit on U shaped curves. It is shown that, irrespective of alkyl chain length, counterion and polar head group of the ionic surfactant, the dependence of CMCs on intensive variables can be expressed according to [CMC (X)/CMC*(X)-1] = \1-X/X*/η where η is an exponent and X the intensive parameter into account. The above fit allows the prediction of the dependence of CMCs on intensive variables in a wide range of experimental conditions. In addition, accurate values for the entropy of micelle formation can be obtained.