Interaction of Nonionic Surfactants and Hydrophilic Ionic Liquids in Aqueous Solutions: Can Short Ionic Liquids Be More Than a Solvent?

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• 作者：Francesc Comelles ; Isabel Ribosa ; Juan Jos茅 Gonz谩lez ; Maria Teresa Garcia
• 刊名：Langmuir
• 出版年：2012
• 出版时间：October 16, 2012
• 年：2012
• 卷：28
• 期：41
• 页码：14522-14530
• 全文大小：396K
• 年卷期：v.28,no.41(October 16, 2012)
• ISSN：1520-5827

文摘

The interaction between an ethoxylated nonionic surfactant (C_12鈥?4EO₈) and three conventional hydrophilic imidazolium-based ionic liquids (bmim-octyl SO₄, bmim-methyl SO₄, and bmim-BF₄) in aqueous solution has been investigated. In most of the reported studies where a surfactant is dissolved in an ionic liquid aqueous solution, conventional ionic liquids are merely considered to be solvents. Consequently, the resulting critical micelle concentration (cmc) is considered to be that of the surfactant. However, given that the three ionic liquids selected showed the typical shape of a surface-active compound when the surface tension was plotted against concentration, the role of these compounds as secondary surfactants and consequently the possibility of mixed-micelle formation have been investigated. Different series of experiments where a surfactant and an ionic liquid were combined in a wide range of mole ratios have been performed and treated as typical binary surfactant systems in aqueous solution. It has been found for the three surfactant/ionic liquid systems that depending on the surfactant mole fraction, 伪₁, attractive or repulsive interactions in mixed-micelle formation are produced. Therefore, when we select the appropriate 伪₁ these systems can be adjusted to a given application, depending on whether monomers or micelles are mainly required.