Electrical conductivity of dilute and semidilute aqueous polyelectrolyte solutions. A scaling theory approach

We study the low-frequency electrical conductivity of flexible charged polymer chains in salt-free aqueous solutions on the basis of the Manning counterion condensation model, taking into account a dynamic scaling description recently proposed by Dobrynin, Colby, and Rubinstein (Macromolecules 1995, 28, 1859) of the polyion configuration in different concentration regimes covering both the dilute and semidilute regions. We compare the prediction of this model with conductivity data obtained for salt-free aqueous solutions of poly(L-lysine) of four different molecular weights (from 4 to 167 kD), over an extended concentration interval to cover the different regimes, from dilute to semidilute unentangled solutions. Our predictions are found to compare favorably well with the observed conductivity behavior over the whole concentration range investigated.