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)±]. The exponent ± depends on polymer length L and solvent ionic strength only through the ratio x==L/Lp, where Lp is the persistence length, and crosses over from ±1 for stiff chains (x1) to ±0.44±0.02 in the self-avoiding-walk regime x1, the latter in accord with a simple scaling theory of polymer statistics and dynamics. © 1990 The American Physical Society.