Reversible Switching of Amphiphilic Self-Assemblies of Ionic Liquids between Micelle and Vesicle by CO2

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• 作者：Yunlei Shi ; Dazhen Xiong ; Huiyong Wang ; Yang Zhao ; Jianji Wang
• 刊名：Langmuir
• 出版年：2016
• 出版时间：July 12, 2016
• 年：2016
• 卷：32
• 期：27
• 页码：6895-6901
• 全文大小：348K
• 年卷期：0
• ISSN：1520-5827

文摘

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 [C_nMDEA]⁺ (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 [C_nMDEA][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.