Nonaqueous ionic liquid microemulsions of 1-butyl-3-methylimidazolium tetrafluoroborate, toluene and ethanol

Abstract

The phase behavior of the ternary system consisting of the hydrophilic ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF 4 ), toluene and ethanol was investigated. Single-phase microemulsion and multiphase regions were observed in the ternary phase diagram. To the best of our knowledge, this is the first report on nonaqueous IL microemulsions prepared in the absence of traditional surfactants. The microstructures and structural transitions of the microemulsion system were investigated by cyclic voltammetry, pulse field gradient spin-echo nuclear magnetic resonance and electrical conductivity measurements. The microemulsions exhibit IL-in-toluene (IL/O), bicontinuous (BC) and toluene-in-IL (O/IL) microstructures, similarly to traditional surfactant-based microemulsions. The three kinds of microstructures were confirmed from freeze-fracture electron microscopy observations. A pearl necklace-like structure was observed in the BC microemulsion. The polarity of bmimBF 4 domains in the IL/O microemulsion was investigated by UV-visible absorption spectroscopy using methyl orange as a probe. It was found that the polarity was lower than that of the bulk bmimBF 4 , and it increased with increasing bmimBF 4 content at a constant toluene-ethanol ratio.

Development of Coarse‐Grained Force Field by Combining Multilinear Interpolation Technique and Simplex Algorithm

“…Similarly, the diffusion coefficient of oil D o also increase monotonically as the concentration of oil becomes higher, but D o is more continuous than D w . In summary, the response of SCFME diffusion to concentration is consistent with those observed for SBMEs and SFMEs from electrical conductivity and cyclic voltammetry studies.…”

“…Besides structures, many other properties such as surface tension, diffusion, conductivity, and evaporation rate undergo a progressive change when the concentration ratio of the water/oil mixture varies. To test whether the SCFME in our simulation has such feature, we calculated the diffusion coefficient of water D w as a function of M w .…”

A surfactant-free microemulsion composed of isopentyl acetate, n-propanol, and water

“…The uncertainty in locating the boundaries of different subregions is estimated to be less than 10%. The microstructures and structural transition observed herein are similar to those reported for other SFMEs 2,7,9,[13][14][15]19,21 and SBMEs. 33,35,[38][39][40]…”

“…Subsequently, the formation of SFMEs was conrmed in some surfactant-free ternary systems. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] The structures, properties, and formation mechanism of SFMEs have been investigated. 1,2,[22][23][24] It has been preliminarily demonstrated that the structures and properties of SFMEs are similar to those of traditional SBMEs to some extent.…”

“…2 For instance, similar to SBMEs, 3 SFMEs can exhibit three structures: oil-inwater (O/W), bicontinuous (BC), and water-in-oil (W/O) structures, and the three kinds of structures can be translated into each other with change in the composition of the system. 7,[9][10][11][13][14][15]19,21 In addition, similar to SBMEs, 25 SFMEs are expected to have extensive potential applications 2 such as in enzymatic reactions, 26 chemical reactions, [27][28][29] and nanoparticle synthesis. [30][31][32] In particular, SFMEs when used as reaction media may avoid some problems, such as complex separation and purication procedures, possible ecotoxicity, and high material cost, caused by the existence of large amounts of surfactants (>10 wt%) in SBMEs.…”