Phase Behavior and Microstructure of Microemulsions Containing the Hydrophobic Ionic Liquid 1-Butyl-3-methylimidazolium Hexafluorophosphate

The phase behavior and microstructure of the ternary system water/1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6)/Triton X-100 was studied as a function of temperature and ionic liquid (IL) mass fraction α. In the present study, a hydrophobic IL instead of commonly used organic solvents such as n-alkanes is used. The fish-shaped region is distorted at low and high values of α, whereas it is symmetric at intermediate α. With increasing α, the extension of the three-phase region decreases regarding the surfactant concentration range, whereas it increases regarding the temperature range. For comparison the phase behavior of two ternary water/bmimPF6/alkyl oligoethyleneoxide (C i E j ) systems has been investigated. Our results are compared with those obtained for water/n-alkane/C i E j and IL/n-alkane/C i E j systems, respectively.