A surprising mixed solvent effect, both in its magnitude and direction, has been found in the phase diagram of the ternary mixture of ([C4mim][PF6] + (water + ethanol)). For a molar ratio of 1∶1 of water to ethanol, the co-solvent effect in the near-critical demixing temperature can be as large as 80 K.
Najdanovic-Visak, V., Esperança, J. M. S. S., Rebelo, L. P. N., Da Ponte, M. N., Guedes, H. J. R., Seddon, K. R., & Szydlowski, J. (2002). Phase behaviour of room temperature ionic liquid solutions: An unusually large co-solvent e3ect in (water + ethanol). Physical Chemistry Chemical Physics, 4, 1701-1703 . https://doi.org/10.1039/b201723g