Diffusion coefficients of micelles composed of fluorocarbon surfactants with cyclic voltammetry

Cyclic voltammetry of(ferrocenylmethyl)trimethylammonium bromide (FcTAB) was applied on anionic micelle systems in order to reveal the solution properties of micelles composed of fluorocarbon surfactants. Diffusion coefficients of FcTAB decreased with micelle formation because the cationic FcTAB diffuses together with micelles. The diffusion coefficient abruptly decreased with the addition of sufficient salt, suggesting an increase in micelle size and a transition of micelle shape. The diffusion coefficient for mixed micelles composed of fluorocarbon and hydrocarbon surfactants decreased considerably compared to those for their single surfactant systems. The micelle size of fluorocarbon surfactants, especially for lithium 1,1,2,2-tetrahydroheptadecafluorodecyl sulfate, significantly depended on the salt concentrations and the compositions of the mixtures. Cyclic voltammetry is a simple and useful method to evaluate the micelle diffusion coefficients of fluorocarbon surfactants which can hardly be estimated by dynamic-light-scattering measurements.