Hexagonal liquid crystalline phases formed in ternary systems of Brij 97-water-ionic liquids.
Phase diagrams of two ionic liquids: hydrophobic 1-butyl-3-methylimidazolium hexafluorophosphate (bmim-PF(6)) and relatively hydrophilic 1-butyl-3-methylimidazolium tetrafluoroborate (bmim-BF(4)) in aqueous solutions of Brij 97 were determined at 25 degrees C. Two hexagonal liquid crystalline phases formed in bmim-PF(6)- and bmim-BF(4)-containing ternary systems were investigated by means of small-angle X-ray scattering (SAXS) and rheological techniques, with comparison of composition and temperature effects. From analysis of the SAXS data, bmim-PF(6) is dominantly penetrated between the oxyethylene chains of surfactant molecules, whereas bmim-BF(4) is mainly located in the water layer of hexagonal phases. The strength of the network of hexagonal phase formed in the Brij 97/water/bmim-BF(4) system is appreciably stronger than that of the Brij 97/water/bmim-PF(6) system, indicated by the smaller area of the surfactant molecule at the interface and the higher moduli (G', G' '). Temperature has a converse effect on the lattice parameters of the two hexagonal phases.
Wang
Zhongni
Z
Key Laboratory for Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, People's Republic of China. zhongniw@hotmail.com
Liu
Feng
F
Gao
Yanan
Y
Zhuang
Wenchang
W
Xu
Limei
L
Han
Buxing
B
Li
Ganzuo
G
Zhang
Gaoyong
G