THE EFFECT OF CHEMICAL-STRUCTURE UPON THE THERMODYNAMICS OF MICELLIZATION OF MODEL ALKYLARENESULFONATES .3. DETERMINATION OF THE CRITICAL MICELLE CONCENTRATION AND THE ENTHALPY OF DEMICELLIZATION BY MEANS OF MICROCALORIMETRY AND A COMPARISON WITH THE PHASE-SEPARATION MODEL

This paper reports on critical micelle concentrations and enthalpies of micellization of model sodium alkylarylsulfonates in water as determined by means of an automatic titration microcalorimeter. The experimental enthalpies are compared with those predicted by the phase separation model of micelle formation. It is observed that the phase separation model is not adequate enough since in most cases it systematically underestimates the experimental enthalpies. Suggestions are made to improve the model; these include the incorporation of counterion binding, the use of activity coefficients, and ion interaction parameters. The use of an even more sophisticated model which includes the heterodispersity of micelles is not envisaged at this moment as micellar size distributions of alkylarylsulfonates are not known. © 1991.