title: A high-pressure infrared spectroscopic study on the interaction of ionic liquids with PEO-PPO-PEO block copolymers and 1,4-dioxane.
abstract: We have investigated the effect of pressure on imidazolium C-H---O interactions in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (EMI(+)TFSA(-))/L64 and EMI(+)TFSA(-)/1,4-dioxane mixtures. The addition of Pluronic L64 to EMI(+)TFSA(-) leads to appreciable changes in band frequencies and shapes of the imidazolium C-H stretching bands. A possible explanation is the formation of C-H---O interactions between imidazolium C-H groups and oxygen atoms of polyethylene oxides (PEOs). In other words, L64 can be added to change the relative contribution of the isolated and associated components of EMI(+)TFSA(-). In contrast to L64, the oxygen atoms of 1,4-dioxane cannot perturb the local structures of imidazolium C-H groups of EMI(+)TFSA(-) and the association configuration is still favored in the presence of 1,4-dioxane. As the pressure is elevated, 1,4-dioxane molecules tend to associate with themselves and TFSA(-) interacts with EMI(+) to form associated configurations. Our results suggest the formation of association between EMI(+) cation and L64 and the complexes are stable up to the pressure of 2.5 GPa.
authors.affiliation: Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
authors.forename: Jyh-Chiang
authors.initials: JC
authors.lastname: Jiang
authors.forename: Sz-Chi
authors.initials: SC
authors.lastname: Li
authors.forename: Pao-Ming
authors.initials: PM
authors.lastname: Shih
authors.forename: Tzu-Chieh
authors.initials: TC
authors.lastname: Hung
authors.forename: Shu-Chieh
authors.initials: SC
authors.lastname: Chang
authors.forename: Sheng Hsien
authors.initials: SH
authors.lastname: Lin
authors.forename: Hai-Chou
authors.initials: HC
authors.lastname: Chang