Motivated by the pioneering work of Corti and Degiorgio, my group in the Physics Dept. and Dr. Bunton's group in the Chemistry Dept. at UC Santa Barbara engaged in a decade-long collaborative study of the dependence of intermicellar repulsive interactions on surfactant/counterion composition, using the emerging technique of dynamic light scattering (DLS). The micellar diffusivity, D, was observed to increase linearly with surfactant concentration over ranges of electrolyte concentration where the added ions 'screened' to varying degrees the intermicellar electrostatic repulsions without substantially growing the micelles. Linear interaction theory and later the more advanced hypernetted chain approximation were used to obtain the fractional micellar ionization as a function of surfactant composition and, especially, counterion type.  Systems investigated included CTABr, CTACl and CTAOH. Underlying DLS principles, application details and representative results will be reviewed.

So many (small) micelles ... so little (autocorrelation) time ...Studies of micellar size, intermicellar interactions and electric charge by dynamic light scattering (DLS)

239th National Meeting (2010)

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