| Abstract
| - The “ordinary−extraordinary” transition in the observed diffusivity of polyelectrolytesolutions was studied by dynamic light scattering using the model system of sodium polystyrene sulfonate(SPS) in N-methylformamide (NMF). NMF was chosen because it has a high dielectric constant thatvaries strongly with temperature, and it was hoped that an organic solvent would better solvate thechain backbone. Two diffusion coefficients corresponding to the previously reported fast and slow modeswere observed at all salt concentrations. This is in contrast to previous work where the slow relaxation“appeared” only when the concentration of added salt is less than the critical concentration, CDD, derivedby Drifford and Dalbiez. In this work, the absolute amplitude of the slow mode was nearly constant atsalt concentrations both above and below the transition in general agreement with Sedlak's recent surveyof aqueous SPS solutions.
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