The effects of counterion exchange on charge stabilization for anionic surfactants in nonpolar solvents

Hypothesis: Sodium dioctylsulfosuccinate (Aerosol OT or NaAOT) is a well-studied charging agent for model poly(methyl methacrylate) (PMMA) latexes dispersed in nonpolar alkane solvents. Despite this,few controlled variations have been made to the molecular structure. A series of counterion exchanged analogs of NaAOT with other alkali metals (lithium, potassium, rubidium, and cesium) were prepared, and it was expected that this should influence the stabilization of charge on PMMA latexes and the properties of the inverse micelles. Experiments: The electrophoretic mobilities of PMMA latexes were measured for all the counterion exchanged AOT analogs, and these values were used to calculate the electrokinetic or f potentials. This enabled a comparison of the efficacy of the different surfactants as charging agents. Small-angle scattering measurements (using neutrons and X-rays) were performed to determine the structure of the inverse micelles, and electrical conductivity measurements were performed to determine the ionized fractions and Debye lengths.