Structure, Dynamics, and Composition of Large Clusters in Polyelectrolyte-Surfactant Systems

Abstract

Mixtures of oppositely charged polyelectrolyte (PE) and surfactant show rich structural behavior. The dynamics of such self-assembled structures can be quite complex. For example, using dynamic light scattering (DLS), we observed a slow collective relaxation mode for mixtures of the cationically charged PE JR 400 and the anionic surfactant SDS if the concentration of the system is sufficiently high and a small excess of PE charges is present. A similar mode is observed by using fluorescence correlation spectroscopy (FCS). However, a large quantitative discrepancy is observed between the values obtained from DLS and FCS. In this paper, we are investigating the connection between these slow relaxation modes and the formation of large micrometer sized structures which have been investigated using ultrasmall-angle neutron scattering (USANS), and the discrepancies between results from DLS and FCS are explained.