Dielectric dispersion properties of aqueous polyelectrolyte solutions

Abstract

The conductance of aqueous polyelectrolyte solutions was determined at 25°C in the frequency range 400 Hz-100 kHz; both capacitance and conductance were determined between 0.6 and 30 MHz. Various salts of polystyrenesulphonic acid, polyvinylsulphonic acid and polyacrylic acid with univalent counterions (H⁺, Li⁺, Na⁺, K⁺, Cs⁺, (CH₃)₄N⁺, (nC₄H₉)₄N⁺), were investigated. Whereas in the low frequency range the dielectric properties depend on macromolecular size, the dielectric dispersion in the megacycle range is independent of degree of polymerization and is ascribed to the relaxation of the ionic atmosphere surrounding the macroion. The systems investigated are characterized by a spectrum of relaxation times. Above a certain value of the charge density the dispersion becomes independent of the degree of ionization of ionogenic groups on the chains. The average relaxation times decrease with increasing concentration but increase with increasing radius of the hydrated counterions.