The effects of concentration, relative permittivity and temperature on the transport properties of sodium polystyrenesulphonate in methanol-water mixed solvent media

Precise measurements on the electrical conductivity of solutions of sodium polystyrenesulphonate in methanol-water mixed solvent media containing 8, 16, 25, and 34 wt.% of methanol at 308.15, 313.15, 318.15, and 323.15 K are reported. The degree of substitution of sodium polystyrenesulphonate used was 1, and the concentrations were varied from similar to 2.0 x 10(-4) to similar to 4.0 x 10(-3) monomol l(-1). The results showed a slight and monotonous increase in the equivalent conductivity with decreasing polyelectrolyte concentration. The applicability of the Manning's theory for salt-free polyelectrolyte solution was examined and a major discrepancy against the theory was observed. The calculated values of the equivalent conductivity deduced on the basis of this theory were found to be lower than the experimental ones. Possible reasons for this discrepancy have been discussed. The effects of the temperature and relative permittivity of the medium on the equivalent conductivity were also investigated. Estimation of the fractions of uncondensed counterions provides important insight regarding the solution behavior of the polyelectrolyte in methanol-water mixtures.