2002 Volume 51 Issue 2 Pages 133-140
The aggregation behavior of molecular assemblies formed between oppositely charged surfactants in water was investigated through measurements of the electrochemical behavior of the cationic component, 11-ferrocenylundecyltrimethylammonium bromide (FTMA), in mixtures with the anionic component, sodium dodecylbenzenesulfonate (SDBS). FTMA/SDBS mixture was found to form various types of molecular assemblies such as micelles and vesicles in aqueous solutions depending on the mixing ratio. Cyclic voltammogram on FTMA in the molecular assemblies showed that the peak of oxidation current due to FTMA/SDBS complexes consisting of vesicles is observed on the anodic side of that due to FTMA moleculs consisting of mixed micelles. Moreover, electrochemical measurements on the total surfactant concentration dependence of the phase behavior in solutions of 1:0.4 molar ratio of FTMA and SDBS revealed that vesicles begin to form at a concentration (critical aggregation concentration; cac) much lower than the critical micelle concentration (cmc) of FTMA alone and a phase containing both vesicles and micelles appears at a concentration higher than the cmc.