Micellization in Water-Polar Organic Solvent Binary Mixtures

Abstract

Micellization of several monomeric surfactants in water-polar organic solvent mixtures has been investigated by different authors. The gradual replacement of water with other polar solvents allows one to explore the effects of solvent addition on the self-aggregation process in a wide bulk phase composition. For those polar organic solvents which are localized mainly in the bulk phase of the micellar solutions (they do not incorporate into the micellar aggregates), the variations in the cohesive energy density of the binary mixture, upon increasing the organic solvent content, seems to play a key role in the observed Gibbs energy of micellization, ΔG°M, changes. The cohesive energy density can be measured through the Gordon parameter. For a given surfactant, ΔG°M values obtained in several binary water-organic solvent mixtures can be fitted together. This ΔG°M vs. cohesive energy density correlation will permit the prediction of the variations in the Gibbs energy of micellization of monomeric surfactants upon addition of known quantities of a given polar organic solvent.