CONDUCTIVITY AND DYNAMIC LIGHT-SCATTERING-STUDIES ON HOMOLOGOUS ALKYLBENZYLDIMETHYLAMMONIUM CHLORIDES IN AQUEOUS-SOLUTIONS

The critical micelle concentration and ionization degree of micelles f ormed by decyl-, dodecyl- and tetradecylbenzyldimethylammonium chlorid es in aqueous solutions at 298 K have been determined conductometrical ly. The hydrodynamic radii of the micelles have been estimated from qu asi-elastic light scattering data obtained for the surfactants in aque ous sodium chloride solutions. Both techniques yield results indicatin g a high degree of ionization of the micelles, suggesting that the ben zyl group acts as a second hydrophobic substituent al the head group o f the surfactant and plays a role similar to that of a second alkyl ch ain in double-chained cationic surfactants.