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Structural Studies of 1‐Butyl‐3‐methylimidazolium Tetrafluoroborate/TX‐100/ p ‐Xylene Ionic Liquid Microemulsions
Author(s) -
Gao Yan'an,
Zhang Jin,
Xu Hongyan,
Zhao Xueyan,
Zheng Liqiang,
Li Xinwei,
Yu Li
Publication year - 2006
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200600120
Subject(s) - microemulsion , ionic liquid , chemistry , dynamic light scattering , tetrafluoroborate , xylene , analytical chemistry (journal) , pulmonary surfactant , materials science , organic chemistry , nanoparticle , toluene , nanotechnology , biochemistry , catalysis
10.1002/cphc.200600120.abs The ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate (bmimBF 4 ) forms nonaqueous microemulsions with p ‐xylene, with the aid of the nonionic surfactant TX‐100. The phase behavior of the ternary system is investigated, and three microregions of the microemulsions—ionic liquid‐in‐oil (IL/O), bicontinuous, and oil‐in‐ionic liquid (O/IL)—are identified by conductivity measurements, according to percolation theory. On the basis of a phase diagram, a series of IL/O microemulsions are chosen and characterized by dynamic light scattering (DLS). The size of aggregates increases on increasing the amount of added polar component (bmimBF 4 ), which is a similar phenomenon to that observed for typical water‐in‐oil (W/O) microemulsions, suggesting the formation of IL/O microemulsions. The microstructural characteristics of the microemulsions are investigated by FTIR and 1 H NMR spectroscopy. The results indicate that the interaction between the electronegative oxygen atoms of the oxyethylene (OE) units in TX‐100 and the electropositive imidazolium ring may be the driving force for the solubilization of bmimBF 4 into the core of the TX‐100 aggregates. In addition, the micropolarity of the microemulsions is investigated by using methyl orange (MO) as a UV/Vis spectroscopic probe. A relatively constant polarity of the microemulsion droplets is obtained in the IL microemulsion. Finally, a plausible structure for the IL/O microemulsion is presented.