Reversible Switching of Amphiphilic Self-Assemblies of Ionic Liquids between Micelle and Vesicle by CO2.
The creation of CO2-responsive materials that undergo structural transition between micelle and vesicle is of great importance from both theoretical and practical points of view. In this work, we have developed a series of CO2-responsive single-tailed amphiphilic ionic liquids (ILs) composed of N-alkyl-N-methyldiethanolamine cation [CnMDEA](+) (n = 8, 10, 12, 14, 16, 18) and 2-pyrrolidinone [2-Pyr](-) anion. The aggregation behavior and self-assembly structures of the ILs in aqueous solution have been investigated by conductivity, surface tension, dynamic light scattering, cryogenic transmission electron microscopy, small-angle X-ray scattering, and nuclear magnetic resonance spectroscopy. For the first time, CO2 driven reversible switching of self-assembly between spherical micelle and unilamellar vesicle is found for [CnMDEA][2-Pyr] (n = 16, 18) in aqueous solutions at 20 °C and atmospheric pressure. It is shown that the mechanism behind the reversible micelle to vesicle transition involves the formation of carbamate anion from the reaction between [2-Pyr](-) and CO2.
Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University , Xinxiang, Henan 453007, P. R. China.
Yunlei
Y
Shi
Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University , Xinxiang, Henan 453007, P. R. China.
Dazhen
D
Xiong
Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University , Xinxiang, Henan 453007, P. R. China.
Huiyong
H
Wang
Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University , Xinxiang, Henan 453007, P. R. China.
Yang
Y
Zhao
Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University , Xinxiang, Henan 453007, P. R. China.
Jianji
J
Wang