Soluting-out/in Effects in Aqueous Ionic Liquid +Polymer Solutions

Polymer-IL aqueous biphasic systems (ABS) are formed by the combination of distinctpairs of polymers and ionic liquids in aqueous media. These ABS have a series of advantagesrelative to the conventional polymer-polymer or polymer-salt ABS. Depending on the structuralfeatures of polymers and ionic liquids, both the ionic liquids and polymers can act as the saltingoutspecies. Based on a compilation and analysis of the data hitherto reported, we discuss themain issues which govern the phase behavior of these systems. In this respect the effect ofstructure and molecular weight of polymer, temperature, structure of anion and cation of ionicliquid on the liquid-liquid equilibria phase behavior of these sys-tems is discussed. Based on theliquid-liquid and vapor-liquid equilibria behavior of the ternary polymer-IL-water systems, themolecular-level mechanisms behind the formation of these ABS will be discussed. It was shownthat, the salting-in/-out effects in these systems are controlled by a complex interplay ofpolymer-IL, polymer-water and IL-water interactions.