SOLUTION BEHAVIOR OF CRYSTALLINE SURFACTANT MOLECULAR-COMPLEXES - ELECTRIC-CONDUCTIVITY MEASUREMENTS OF AQUEOUS-SOLUTIONS OF MOLECULAR-COMPLEXES BETWEEN CATIONIC SURFACTANT AND AROMATIC ADDITIVE SYSTEMS

From systems used in the conventional treatment of solubilization, quaternary ammonium cationic surfactants and several aromatic substances (solubilizates) provided many types of crystalline molecular complexes. The crystal structures have recently been revealed by X-ray analysis. The crystalline surfactant complexes, new chemical species, exhibited properties analogous to those of any surface active agent in their aqueous solutions. In a plot of the electric conductivity(kappa) against the molar concentration, these species show a characteristic break point which corresponds to their cmc. Moreover, the obtained cmc's satisfied the well-known relation of log(cmc) = A - BN, among their complex homologous series. These facts imply that the surfactant complex is clearly a different kind of surfactant species from the original one. In addition, the aqueous solutions of any complex species demonstrated a deeply suggestive profile of kappa-concentration behaviors. They are perfectly identical to the behavior of a solubilized solution which is composed of the same component ratio as the complexes. These facts firmly support the conclusion that this phenomenon, commonly referred to as solubilization, is not special but is easily interpreted in terms of simple dissolution of these molecular complex species. (C) 1995 Academic Press, Inc.