INFLUENCE OF SUBSTITUTED AMMONIUM-IONS ON THE THERMODYNAMICS AND KINETICS OF MICELLES OF PERFLUORATED OCTANESULFONATE

Conductivity and chemical relaxation measurements are reported on surfactant solutions containing the perfluorated anion C8F17SO3 -and the counterions Li+, CH3NH3+, (CH3)2NH2+, (CH3)3NH+, (CH3)4N+, C2H5NH3+, (C2H5)2NH2+, (C2H5)3NH+ (C2H5)4N+ and C3H7NH3+. For most of the studied systems two relaxation times were observed which were attributed to the shift of the micellar distribution curve and the change of the concentration of the micellar species. The kinetic data are discussed on the basis of the theory for micelle formation that was recently given by G. Aniansson and S. Wall. The data permit the evaluation of the micellar aggregation number n, the halfwidth of the micellar distribution curve α, the concentration of the micellar nuclei Cr and their aggregation number r, the residence times of the surfactant molecules in the micelle and the rate constant for the recombination of a monomer with the micelle. The residence times of the perfluorated anion and the aggregation number of the micelles increase with the substitution of -atoms by alkylgroups on the ammonium ions. The micelles grow in size with decreasing temperature. For most of the counterions, the micelles are non-spherical. © 1978, Akademische Verlagsgesellschaft, Wiesbaden