Effect of Counterions on Micellization of Pyrrolidinium Based Silicone Ionic Liquids in Aqueous Solutions

详细信息    查看全文

• 作者：Jinglin Tan ; Shengyu Feng
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2014
• 出版时间：June 12, 2014
• 年：2014
• 卷：59
• 期：6
• 页码：1830-1834
• 全文大小：250K
• 年卷期：v.59,no.6(June 12, 2014)
• ISSN：1520-5134

文摘

The micellization of two silicone ionic liquids, 1-methyl-1-[tri(trimethylsiloxy)]- silylpropylpyrrolidinium nitrate (Si₄pyNO₃) and 1-methyl-1-[tri(trimethylsiloxy)]- silylpropylpyrrolidinium acetate (Si₄pyAc), with different counterions was systematically investigated by surface tension and electrical conductivity. Surface tension of water can be reduced almost to 20 mN路m^鈥? with the addition of the silicone ionic liquids, indicating that the silicone ionic liquids exhibit excellent surface activity. The critical micelle concentration (CMC) values of Si₄pyNO₃ are less than those of Si₄pyAc. Electrical conductivity measurements show that the degree of counterion binding (尾) for Si₄pyNO₃ is twice as large as that for Si₄pyAc. Thermodynamic parameters (螖H_m⁰, 螖S_m⁰, and 螖G_m⁰) of micellization derived from electrical conductivities indicate that the micellization for both Si₄pyNO₃ and Si₄pyAc is enthalpy-driven process. The heat capacities, 螖c_m,p⁰, are negative for the two silicone ionic liquids relating to the removal of water accessible nonpolar surfaces. The addition of sodium halides in the aqueous solution decreases CMC remarkably; however, the surface tension at CMC stays the same with the salt-free system.