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SYNOPSISThe influence of divalent salts (MgC12, CaC12, BaC12) on precipitation of polyelectrolyte, poly [ (maleic acid) -a&-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 concen- The solution of 100NaMA/St, is very sensitive to divalent cations, showing a drastic decrease of viscosity, low dehydration, and low c,, values (approximately equivalent to cp) independent of T. More extended and hydrated macromolecules in aqueous solution of 50NaMA/St show a gradual decrease of viscosity, larger dehydratation, and higher c, values (cSc = 0.015-0.5M/L for cp 3 g/L at 298 K) which, however, decrease with the increase of cp and T. The tendency of divalent cations to precipitate the copolymer follows the order Ba2+ > Ca2+ > M8+.The stability of aqueous solution of sulfonated NaMA/St, having the same chain length, increases with the increase of degree of sulfonation. I NTRO D U CTl ONThe precipitation of synthetic polyelectrolytes from aqueous solutions containing multivalent cations decreases their efficiency as auxiliary agents in many applications. In aqueous solutions of polyelectrolytes abound with various interactions, a higher electrostatic potential of polyions attracts cations, causing ~~ ~

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