title: Role of the surfactant structure in the behavior of hydrophobic ionic liquids within aqueous micellar solutions.
abstract: The behavior of an ionic liquid (IL) within aqueous micellar solutions is governed by its unique property to act as both an electrolyte and a cosolvent. The influence of the surfactant structure on the properties of aqueous micellar solutions of zwitterionic SB-12, nonionic Brij-35 and TX-100, and anionic sodium dodecyl sulfate (SDS) in the presence of the "hydrophobic" IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) is assessed along with the possibility of forming oil-in-water microemulsions in which the IL acts as the "oil" phase. The solubility of [bmim][PF(6)] within aqueous micellar solutions increases with increasing surfactant concentration. In contrast to anionic SDS, the zwitterionic and nonionic surfactant solutions solubilize more [bmim][PF(6)] at higher concentrations and the average aggregate size remains almost unchanged. The formation of IL-in-water microemulsions when the concentration of [bmim][PF(6)] is above its aqueous solubility is suggested for nonionic Brij-35 and TX-100 aqueous surfactant solutions.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
authors.forename: Kamalakanta
authors.initials: K
authors.lastname: Behera
authors.forename: Vinod
authors.initials: V
authors.lastname: Kumar
authors.forename: Siddharth
authors.initials: S
authors.lastname: Pandey