Stability of aqueous solutions of poly[(maleic acid)‐alt‐styrene] sodium salts in the presence of divalent cations

The influence of divalent salts (MgCl2, CaCl2, BaCl2) on precipitation of polyelectrolyte, poly[(maleic acid)‐alt‐styrene]sodium salts, NaMA/St, having two degrees of neutralization (100 mass %, 100NaMA/St and 50 mass % 50NaMA/St) from their aqueous solutions, has been investigated. The experiments were performed by variation of the copolymer concentration, cp = 0.005‐0.04M/L, salt concentration, cs = 0.002‐0.4M/L, and temperature, T 298‐333 K. The critical concentrations of salts, csc, used as a measure of solution stability, were determined from turbidimetric measurements, while viscosity and refractive index measurements were used to indicate the changes in dimensions and hydration of polyions, respectively.