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The Effect of Water on the Microstructure of 1‐Butyl‐3‐methylimidazolium Tetrafluoroborate/TX‐100/Benzene Ionic Liquid Microemulsions
Author(s) -
Gao Yan'an,
Li Na,
Zheng Liqiang,
Zhao Xueyan,
Zhang Jin,
Cao Quan,
Zhao Mingwei,
Li Zhen,
Zhang Gaoyong
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600939
Subject(s) - microemulsion , ionic liquid , tetrafluoroborate , molecule , chemistry , hydrogen bond , phase (matter) , pulmonary surfactant , organic chemistry , catalysis , biochemistry
The ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim][BF 4 ]) forms nonaqueous microemulsions with benzene with the aid of nonionic surfactant TX‐100. The phase diagram of the ternary system was prepared, and the microstructures of the microemulsion were recognized. On the basis of the phase diagram, a series of ionic liquid‐in‐oil (IL/O) microemulsions were chosen and characterized by dynamic light scattering (DLS), which shows a similar swelling behavior to typical water‐in‐oil (W/O) microemulsions. The existence of IL pools in the IL/O microemulsion was confirmed by UV/Vis spectroscopic analysis with CoCl 2 and methylene blue (MB) as the absorption probes. A constant polarity of the IL pool is observed, even if small amounts of water are added to the microemulsion, thus suggesting that the water molecules are solubilized in the polar outer shell of the microemulsion, as confirmed by FTIR spectra. 1 H NMR spectroscopic analysis shows that these water molecules interact with the electronegative oxygen atoms of the oxyethylene (OE) units of TX‐100 through hydrogen‐bonding interactions, and the electronegative oxygen atoms of the water molecules attract the electropositive imidazolium rings of [bmim][BF 4 ]. Hence, the water molecules are like a glue that stick the IL and OE units more tightly together and thus make the microemulsion system more stable. Considering the unique solubilization behavior of added water molecules, the IL/O microemulsion system may be used as a medium to prepare porous or hollow nanomaterials by hydrolysis reactions.