Concentration-Dependent Dual Behavior of Hydrophilic Ionic Liquid in Changing Properties of Aqueous Sodium Dodecyl Sulfate
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- 作者：Kamalakanta Behera ; Siddharth Pandey
- 刊名：Journal of Physical Chemistry B
- 出版年：2007
- 出版时间：November 22, 2007
- 年：2007
- 卷：111
- 期：46
- 页码：13307 - 13315
- 全文大小：147K
- 年卷期：v.111,no.46(November 22, 2007)
- ISSN：1520-5207
文摘
Modifying physicochemical properties of aqueous surfactant solutions in favorable fashion by addition ofenvironmentally benign room-temperature ionic liquids (ILs) has enormous future potential. Due to its unusualproperties, an IL may demonstrate a unique role in altering the properties of aqueous surfactant solutions.Changes in the properties of aqueous sodium dodecyl sulfate (SDS), an anionic surfactant, upon addition ofa common and popular "hydrophilic" ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] are presented. Addition of low concentrations of [bmim][BF4] (i.e., 2 wt %) to aqueous SDS resultsin a decrease in critical micelle concentration (cmc) as well as an increase in aggregation number (Nagg) andaverage micellar size. An increase in dipolarity and a decrease in microfluidity of the micellar phase is reportedby solvatochromic fluorescence probes pyrene and 1,3-bis-(1-pyrenyl)propane as up to 2 wt % [bmim][BF4]is added to aqueous SDS. The IL is observed to behave similarly to common electrolytes in the concentrationrange 0 < [bmim][BF4] 2 wt %. A further increase in [bmim][BF4] concentration to 30 wt % results in anincrease in cmc which is accompanied by a decrease in Nagg and average micellar size. Change in themicrofluidity of the micellar phase is observed to become insignificant in this concentration range. Evidenceof the presence of micellar aggregates at such high concentration of [bmim][BF4] is furnished by dynamiclight scattering. The role of an IL in altering the properties of aqueous SDS in the range 2 wt % < [bmim][BF4] 30 wt % is similar to those of polar cosolvents. The concentration-dependent dual role of the IL[bmim][BF4] in altering physicochemical properties of aqueous SDS is demonstrated.