i am working on Polyethylene glycol/ sulfate aqueous two phase partitioning, but with increasing the concentration of the salt (below its critical concentration), crystallization happens, in addition to the formation of two aqueous phases although it is known that that the hydration of the sulfate ions is responsible for the two phases formation. Can this be explained based on stronger kosmotropic properties of the polymer?
Dear Amir:
Do you have a water solution of polyethylene oxide. To this solution you add sodium sulfate. Sodium sulfate (in his layer) reduces dissolving polyethylene oxide, as its hydration decreases. But the effect of the two substances mutually. Polyethylene oxide reduces the hydration of the sodium sulfate (in his layer) and therefore decreases its solubility. It precipitates at a lower concentration than in water. Kosmotropic (order-making) if they contribute to the stability and structure of water-water interactions. Chaotropic agents (disorder-makers) have the opposite effect, disrupting water structure.
System PEO-Na2SO4-H2O
Na2SO4 -. Chaotropic agents (disorder-makers) disrupting water structure to PEO.
PEO - Kosmotropic (order-making) to Na2SO4. They contribute to the stability and structure of water-water interactions.Reduces the hydration of the sodium sulfate.
Best regards.
So many thanks dr. Yuri. I was thinking of the kosmotropic properties of the polymer for dehydration of salts, but could not find any proof for that in literature. I just found few papers dealing with the polymer with suggestions to have kosmotropic properties for proteins, but your answer really clarified the image for me.
Many thanks again
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