DYNAMIC LIGHT-SCATTERING OF FLEXIBLE HIGHLY-CHARGED POLYELECTROLYTES AT INFINITE DILUTION

Literature data on the diffusion behavior at infinite dilution, as mea sured with dynamic light scattering, of flexible highly charged polyel ectrolytes were collected, The apparent diffusion coefficients extrapo lated to zero polyelectrolyte concentration were investigated for diff erent molar masses and ionic strengths. The experimental values were c ompared with theoretical D-0 values calculated with a theoretical proc edure based on the wormlike chain model of Yamakawa and Fujii for the translational friction coefficient. The electrostatic persistence leng th according to Le Bret and the excluded volume theory of Fixman and S kolnick were applied. With the hydrodynamic expansion factor of Barret t and the counterion condensation theory of Manning, satisfactory agre ements were found for D-0 values measured at moderate and low ionic st rengths, Significant deviations occur at high ionic strength (3.1 M), For flexible polyelectrolytes in the ionic strength range from 0.001 u p to 0.5 M the ionic strength dependence of the electrostatic persiste nce length shows a scaling behavior close to kappa(-1). The electrosta tic persistence length appears to be molar mass independent.