STRUCTURE AND DYNAMICS OF POLYMERIZABLE MICROEMULSIONS

The structure of polymerizable microemulsions containing styrene, dode cyltrimethylammonium bromide, and brine is investigated by small-angle neutron scattering (SANS) and quasielastic light scattering (QLS). SA NS measurements suggest that these microemulsions consist of a unimoda l population of swollen micelles that swell uniformly with the additio n of styrene. The double exponential behavior of the autocorrelation f unction measured with QLS experiments is attributed to collective and self-diffusion modes. These modes appear in polydisperse systems at hi gh volume fractions and are enhanced by repulsive interactions. The co llective diffusion coefficient, which increases with added styrene and decreases with salt, depends on both hydrodynamic and thermodynamic i nteractions. The self-diffusion coefficient decreases monotonically wi th added styrene. Adding salt does not affect the size of the swollen micelles but does screen micelle interactions sufficiently that the co ntribution to the autocorrelation function from self-diffusion disappe ars. The experimental values characterizing hydrodynamic interactions agree well with a recently developed theory for small charged spheres.