The Aggregation Behavior of Short Chain Hydrophilic Ionic Liquids in Aqueous Solutions

In this paper, aggregation behaviors of aqueous solutions of short chain hydrophilic Ionic Liquids (ILs), 1 – allyl - 3 - methylimidazolium chloride ([Amim]Cl), 1 - ethyl - 3 - methylimidazolium chloride ([Emim]Cl), 1 - butyl - 3 - methylimidazolium chloride ([Bmim]Cl), 1 - butyl - 3 - methylimidazolium tetrafluoroborate ([Bmim]BF4) were investigated using conductivity and laser light scattering. The measurements of conductivity and light scattering were conducted over the whole liquid range, and the Critical Aggregation Concentration (CAC) of aqueous ILs solution determined with the conductivity, was in the order of 2.35mol/L([Amim]Cl) > 2.32mol/L([Emim]Cl) > 2.29mol/L([Bmim]Cl) < 2.54mol/L([Bmim]BF4 ). The CAC vaule of [Bmim]BF4 determined with conductivity was consistent with the result of light scattering. In addition, we proposed aggregation model for illustrating the structural change in the aqueous ILs solutions.