Osmotic coefficients of aqueous polyelectrolyte solutions at low concentrations, 1. Polystyrenesulfonates with mono‐ and bivalent counterions

With the aid of a membrane osmometer, the osmotic coefficients, Φ, of aqueous solutions of polystyrenesulfonic acid and its salts with mono‐ and bivalent counterions were measured at molalities from 1 · 10−2 to less than 1·10−3 mol/kg. The results were inconsistent with published “limiting laws” and a dependence of Φ on the nominal molecular weight of the macroions was observed. The obtained Φ‐values were compared with the data compiled from other studies. The Φ‐values for solutions containing H and Ca counterions were compared with the corresponding Φ‐values obtained cryoscopically to establish the validity of the method used.