ELECTROCHEMICAL STUDY OF THE MICELLIZATION OF HEXADECYLPYRIDINIUM BROMIDE IN THE PRESENCE OF SOME CROWN-ETHERS

A membrane electrode selective to hexadecylpyridinium bromide was used to study the micellization of the surfactant in the presence of varyi ng concentrations of crown ethers 15-crown-5, dicyclohexyl-18-crown-6 and dicyclohexyl-24-crown-8 at 27 degrees C. The critical micelle conc entration of surfactant was largely influenced by the crown ethers use d, indicating their participation in the structure of the resulting mi celle. The degree of attachment of crown ethers to the surfactant in t he micellar structure was found to be 1. An estimation of the K-f for the 1:1 surfactant-crown interaction in the micellar region is reporte d. The degree of counter ion dissociation was found to increase with t he crown ether concentration, and with the nature of macrocyclic ligan ds in the order 15-crown-5 < dicyclohexyl-18-crown-6 < dicyclohexyl-24 -crown-8. There was also some evidences for a rather strong interactio n between dicyclohexyl-24-crown-8 and the surfactant in the submicella r concentration ranges in solution.