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Surfactant-free Microemulsions of 1-butyl-3-methylimidazolium Hexafluorophosphate, Propylamine Nitrate, and Water

Jie Xu, Huanhuan Deng, Yunlei Fu, Yuquan Chen, Jing Zhang, Wanguo Hou

Soft Matter. 2017 Mar 8;13(10):2067-2074.

PMID: 28217785

Abstract:

Generally, surfactants (or amphiphiles) are believed to be necessary components of microemulsions. However, it has been demonstrated that, in the absence of traditional surfactants, microemulsions can also form from a ternary system of two immiscible fluids (i.e., oil and water phases) and an amphi-solvent, but the current understanding of such surfactant-free microemulsions (SFMEs) is very limited. Herein, we report an SFME consisting of the hydrophobic ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), the protic IL propylamine nitrate (PAN), and water, in which bmimPF6 and PAN are used as the oil phase and the amphi-solvent, respectively. The microstructures and structural transitions of the SFME were investigated using cyclic voltammetry, fluorescence spectroscopy, and ultraviolet-visible spectroscopy. The SFME exhibited water-in-bmimPF6 (W/IL), bicontinuous (BC), and bmimPF6-in-water (IL/W) microstructures, depending on the composition of the ternary system, similar to the case of traditional surfactant-based microemulsions (SBMEs). The three kinds of microstructures were confirmed by cryogenic transmission electron microscopy (cryo-TEM) observations. To the best of our knowledge, this is the first report on SFMEs composed of two ILs as components, especially where one is used as the amphi-solvent.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP174501645 1-Butyl-3-methylimidazolium hexafluorophosphate 1-Butyl-3-methylimidazolium hexafluorophosphate 174501-64-5 Price
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