Ion Bridging Effects on the Electroviscosity of Flexible Polyelectrolytes

An experimental study is carried out to investigate the effect of added salt on the viscosity and microstructure of sodium poly styrenesulfonate solutions. The emphasis is placed on the valence of counterions to seek the existence of bridging effects associated with ion multivalence. To amplify the possible bridging effect, a mixture of water and glycerol is used as a solvent for viscosity experiments because of the lower dielectric constant of the mixture. The viscosity order with respect to the valence of added cations changes, depending on the polymer and salt concentrations. This is explained by the electroviscous effects along with the competition between the intra- and intermolecular association due to the bridging phenomenon.