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Ionic Liquids in Polyethylene Glycol Aqueous Solutions: Salting-in and Salting-out Effects


Changes of the fluid phase behaviour of polyethylene glycol (PEG) aqueous solutions – viz. critical solution temperature shifts at atmospheric pressure – were produced by the addition of different ionic liquids, namely 1-ethyl-3-methylimidazolium ethyl sulfate and 1-alkyl-3-methylimidazolium chloride (alkyl = ethyl to decyl). The addition of ionic liquids with long alkyl chains improves the solubility of PEG in water (salting-in effect), whereas the impact of short-chain ionic liquids is usually the contrary (salting-out effect). The results are interpreted taking into account the kosmotropic (water-structuring) or chaotropic (water-structure-breaking) nature of ionic liquids, as compared to other inorganic salts.

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Correspondence to José N. Canongia Lopes or Luis Paulo N. Rebelo.

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Visak, Z., Canongia Lopes, J. & Rebelo, L. Ionic Liquids in Polyethylene Glycol Aqueous Solutions: Salting-in and Salting-out Effects. Monatsh. Chem. 138, 1153–1157 (2007).

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  • Keywords. Ionic Liquids; Salting-out effects; Aqueous PEG solutions; Kosmotropic and chaotropic salts.