title: Tuning phase behaviour of PEG-functionalized ionic liquids from UCST to LCST in alcohol-water mixtures.
abstract: Thermo-responsive materials with reversible phase transition in molecular solvents are of great importance for catalysis reaction, product separation, and catalyst recycling among others. In this work, liquid-liquid phase transition of PEG-functionalized ionic liquids [PEGm(mim)2][NTf2]2(m = 200, 400, 600, 800, 1000) in aliphatic alcohol (ethanol, 1-propanol or isopropanol) and in aqueous aliphatic alcohol was investigated by turbidity and dynamic light scattering (DLS) measurements, and the effects of the alkyl chain length of the alcohol molecules and molecular weight of the PEG middle block of the ionic liquids on the phase transition behaviour were examined. It was found that these ionic liquids exhibited a unique UCST phase transition in the aliphatic alcohol, but their liquid-liquid phase transition behaviour could be tuned precisely from UCST to LCST in aqueous aliphatic alcohol. Furthermore, temperature-dependent FT-IR and/or1H NMR measurements were performed to understand the possible origin of phase behavior of both [PEGm(mim)2][NTf2]2in the aliphatic alcohol and [PEG800(mim)2][NTf2]2in ethanol-d6/H2O.
authors.affiliation: Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, P. R. China. jwang@htu.cn and School of Civil Engineering, Xinxiang University, Xinxiang, Henan 453003, P. R. China.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Yao
authors.affiliation: Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, P. R. China. jwang@htu.cn.
authors.forename: Huiyong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, P. R. China. jwang@htu.cn.
authors.forename: Guokai
authors.identifier: http://orcid.org/0000-0002-7223-2869
authors.initials: G
authors.lastname: Cui
authors.affiliation: Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, P. R. China. jwang@htu.cn.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Li
authors.affiliation: Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, P. R. China. jwang@htu.cn.
authors.forename: Jianji
authors.initials: J
authors.lastname: Wang