Effects of Inorganic Salts on Phase Separation in Aqueous Solutions of Poly(ethylene glycol).

The effects of a series of sodium salts (NaPO, NaCO, NaSO, NaSO, NaMO, NaCrO, and NaWO) on the phase separation of poly(ethylene glycol) (PEG) solutions in water at PEG concentrations of 0.5 to 30 wt.% were studied. The salts' effects on phase separation are found to correlate with the change in the entropy related to the structural changes in water during anion hydration. The same salts' effects on phase separation in aqueous solutions of branched PEG and polyvinylpyrrolidone at a polymer concentration of 10 wt.% were also examined. The results obtained support the assumption that phase separation in aqueous polymer-salt systems is an entropy-driven process.