Micellar aggregation of Triton X-100 surfactant in imidazolium ionic liquids

In this work we investigated aggregation behavior of a nonionic surfactant Triton X-100 in eighteen imidazolium ionic liquids (ILs) with two to eight carbon atoms in cations alkyl chain, namely 1-ethyl-3-methylimidazolium, [EMIM], 1-butyl-3-methylimidazolium, [PrMIM], 3-methyl-1-propylimidazolium, [BMIM], 1-hexyl-3-methylimidazolium, [PMIM], 3-methyl-1-pentyl-imidazolium, [HMIM], and 1-octyl-3-methylimidazolium, [OMIM], and with different anion substituents, such as tetrafluoroborate, [BF4], hexafluorophosphate, [PF6], bis(trifluoromethanesulfonyl)imide, [Tf2N], and trimethylosulfonate, [TfO]. Surface tension, density and dynamic light scattering measurements were conducted to determine surface and micellar behavior of the surfactant in ionic liquids. In addition, conductometric study gave information on an average number of imidazolium cations associating with each oxyethylene unit of the surfactant. An influence of anion and cation species on the ability of ILs to support Triton X-100 micelle formation was stated and discussed in terms of cohesive energy density.