title: Hexagonal liquid crystalline phases formed in ternary systems of Brij 97-water-ionic liquids.
abstract: 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.
authors.affiliation: Key Laboratory for Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan 250100, People's Republic of China. zhongniw@hotmail.com
authors.forename: Zhongni
authors.initials: Z
authors.lastname: Wang
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Yanan
authors.initials: Y
authors.lastname: Gao
authors.forename: Wenchang
authors.initials: W
authors.lastname: Zhuang
authors.forename: Limei
authors.initials: L
authors.lastname: Xu
authors.forename: Buxing
authors.initials: B
authors.lastname: Han
authors.forename: Ganzuo
authors.initials: G
authors.lastname: Li
authors.forename: Gaoyong
authors.initials: G
authors.lastname: Zhang