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The radiowave dielectric behavior of sodium polyacrylate (NaPAA) aqueous solutions, in an extended concentration range and at various degrees of polymerization, was analyzed in the light of the scaling approach for polyelectrolyte solutions recently proposed by Dobrynin et al. [Macromolecules 1995, 28, 1859]. In the frequency range from 1 MHz to 1 GHz, the observed dielectric relaxation is attributed to the fluctuation of loosely bound counterions over a characteristic correlation length which depends on the polymer concentration. Assuming that free counterions fluctuate on a length scale that is proportional to the correlation length ξ0 of the semidilute solution, we derived power laws for the dielectric strength Δe and the relaxation frequency ν0. In agreement with our recently published data on conductivity, the dielectric data indicate that the effective charge on the NaPAA chains increases as concentration is raised, until the correlation length reaches the size of the electrostatic blob. By comparin...

The d.c. electrical conductivity of polyacrylate sodium salt and poly(acrylic acid) aqueous solutions of different molecular weights from 2 to 200 kD has been investigated in a wide range of polymer concentration, covering both the semidilute (unentangled and entangled) and concentrated regimes. The data have been analyzed on the basis of a modified version of the Manning theory of counterion condensation, to cover the semidilute regime, taking into account scaling arguments recently proposed by Dobrynin et al. (Macromolecules 1995, 28, 1859). This analysis, on the basis of the conductivity model we have adopted, provides evidence for a fraction of free counterions that increases with the polymer concentration until the semidilute-concentrated crossover concentration is reached, suggesting that, in the concentration range investigated, the effective charge on the polyion is dependent on the polymer concentration. Moreover, at the higher concentrations investigated, our data suggest that a regime is attain...