Stretched-exponential relaxation of electric birefringence in polymer solutions

The relaxation of electric birefringence in dilute solutions of a polyelectrolyte is shown to be consistent with a stretched-exponential form, exp[-(t/τ${)}^{\alpha }$]. The exponent α depends on polymer length L and solvent ionic strength only through the ratio x==L/$L_p$, where $L_p$ is the persistence length, and crosses over from α≃1 for stiff chains (x≃1) to α≃0.44±0.02 in the self-avoiding-walk regime x≫1, the latter in accord with a simple scaling theory of polymer statistics and dynamics.