Photon Correlation Spectroscopy of Inverted Micellar Aggregates of AOT in Heptane
Inverted micellar aggregates of AOT in heptane with and without added water were investigated as a function of AOT concentration and molar ratio of water to AOT. Experimental techniques used were Fourier Transform I.R., small angle X-ray spectroscopy, capillary viscometry and mostly photon correlation spectroscopy. FT IR results indicate that even in systems without any added water, inverse micelles of AOT contain about 0.2 to 0.4 water molecules for each molecule of AOT. In systems where there is significant amounts of added water the I.R. spectrum of the sulfonate head group is very close to its spectrum in bulk water. From X-ray measurements it was found that the inverse micelles without added water have a radius of gyration of 8A°. Viscosity and density measurements indicate that solutions of AOT in heptane have higher viscosities than predicted by the hard sphere theories. Photon correlation spectroscopy results give a concentration and solvent independent hydroynamic radius of 16A° and an aggregation number of 16 for inverse micelles without added water.
KeywordsPhoton Correlation Spectroscopy Hydrodynamic Radius Aggregation Number Micellar Aggregate Complete Partitioning
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