Rheology and Characterization of Reverse Micelles

Scott B. Crown1, Caroline R. Szczepanski2, and Patricia A. Darcy2. (1) Department of Chemical Engineering, University of Delaware, Newark, DE 19716, (2) Department of Chemical and Biomolecular Engineering, Lafayette College, Easton, PA 18042

Reverse micelles have many potential applications in biocatalysis, bioprocessing, nanoparticle synthesis, and liquid-liquid extraction. This work investigates the rheology and structural properties of the reverse micelle system composed of cetyltrimethylammonium bromide (CTAB), butanol, cyclohexane, and water. Dynamic light scattering demonstrated that the size of the reverse micelles decreases with increasing ionic strength. Luminescence studies determined an aggregation number for reverse micelles which corresponds well with the value predicted by theory. The static light scattering results show a decrease in scattering intensity with an increase in micellar concentration. This illustrates a change in the reverse micellar morphology. This is supported by the radius of gyration and the trend of the experimental viscosity data. The experimental data was always greater than that predicted by theory for dispersions of spherical particles.