THE MICROSTRUCTURE OF POLYDISPERSE, CHARGED COLLOIDAL SUSPENSIONS BY LIGHT AND NEUTRON-SCATTERING

Structure measurements of a suspension of charged polystyrene spheres with significant polydispersity (16%) are reported for a wide range of particle and added salt concentrations and scattering wave vector. Small angle neutron scattering yielded the structure factors of concentrated samples that have had extensive rheological characterization. A Schulz model of the particle size distribution was used to reduce the intensity data and as a basis for the theoretical fits of the structure factors. Static light scattering measurements yielded the structure factors of diluted, deionized samples. Dynamic light scattering was also performed to study the relaxation of these structures. These measured structures were fit with a recent theory that accounts for both size and charge polydispersity in the suspension. These results and the previous extensive, rheological investigations and physical characterization yield a complete data set on a well-characterized, model system that can be used to test theories of the statics and dynamics of polydisperse colloidal suspensions.