Dynamics of Long-Wavelength Concentration Fluctuations in Solutions of Linear Polymers

Abstract

We report experimental results for a dynamic length scale ${\ensuremath{\xi}}_{H}$ as a function of polymer concentration $c$ for various molecular weight polystyrenes in the two solvents toluene and methyl ethyl ketone. We find that the quantity $\frac{{\ensuremath{\xi}}_{H}}{{R}_{H}}$ is a function only of the reduced concentration $\mathrm{kc}$, where ${R}_{H}$ is the hydrodynamic radius and $k$ is determined from a virial expansion of the diffusion coefficient. However, the dynamic and static length scales are not proportional.