Formation and characterization of epoxidized soybean oil based ionic liquid microemulsions

The phase behavior of the quaternary system consisting of epoxidized soybean oil (ESBO), Triton X-100, n-butanol and ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) was investigated. To the best of our knowledge, this is the first report on the formation and characterization of ESBO based IL microemulsions. Effects of temperature and the mass ratio of surfactant to cosurfactant on phase behavior of ESBO based IL microemulsions were investigated by calculating the single-phase region areas. The results showed that the researched systems presented relatively high Km-dependence and temperature-independence. The microstructures and structural transitions of the microemulsion system were explored by conductivity measurements. Similarly to traditional aqueous IL microemulsions, the microemulsions exhibited IL-in-ESBO (IL/O), bicontinuous (BC) and ESBO-in-IL (O/IL) microstructures. The size and size distribution of bmimBF4 domains in the IL/O microemulsion was investigated by dynamic light scattering. UV–visible absorption spectroscopy with methyl orange as a probe was used to characterize the polarity of researched IL/O microemulsions.