Electrical conductivity and counterion association of cationic polyacrylamide derivatives in aqueous solution

Equivalent electrical conductivity (Λ) is reported for three series of cationic quaternary ammonium polyacrylamide derivatives with MeSO₄ˆ-, Cl−, Br− and I− as counterions at 25 °C, the polyion equivalent concentration C ranging from 5.3 × 10−4 to 6.4 × 10−3 N and from 1.0 × 10−3 to 1.4 × 10−2 N. Equivalent electrical conductivity increases with decreasing polyion equivalent concentration, and the sequence of equivalent electrical conductivity Λ of polyelectrolytes for the same series with different counterions in the range of concentration investigated is: MeSO₄ˆ- > Clˆ- > Brˆ- > Iˆ-. The plots of the counterion–polyion interaction parameter f and degree of dissociation α of polyelectrolyte versus the polyion equivalent concentration C show that the order of counterion associating or binding to polyions for the same polyelectrolyte series in the range of concentration studied is MeSO₄ˆ- < Clˆ- < Brˆ- < Iˆ-. The chemical structures of the polyion have much influence on the Λ, f and α values of the polyelectrolytes.