Abstract: To investigate the influence of different alcohols on the isotropic microemulsion zone of a 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6)/Tween80/toluene system, pseudo ternary phase diagrams of bmimPF6/Tween80/alcohol/toluene systems under different conditions were constructed. Alcohols used were C2H5OH, n-C4H9OH, n-C6H13OH, n-C8H17OH, n-C10H21OH, and i-C5H11OH. Effects of alcohol type and content on the formation of the microemulsion region were investigated. Phase diagrams showed that the microemulsion domain became larger as the Tween80/alcohol weight ratio increased for i-C5H11OH. Different chain lengths of alcohols affected the magnitude of microemulsion regions and this was also dependent on the alcohol solubility in bmimPF6. The single-phase microemulsion area decreased as the alcohol chain length increased. The single-phase region of the ethanol-containing system was the largest among the systems studied. Oil-in-ionic liquid (O/IL) microemulsions, bicontinuous microemulsions, and ionic liquid-in-oil (IL/O) microemulsions in isotropic regions were identified by conductivity measurements. Initial increases of conductivity in ionic liquid microemulsions with increased oil content was due to the oil decreasing ion pairs or ions accumulating in the ionic liquid microemulsion thus increasing the number of charge carriers and improving ionic mobility.

Key words: Microemulsions, Ionic liquids, Alcohol, Pseudo ternary phase diagram