title: Self-assembly of imidazolium-based surfactants in magnetic room-temperature ionic liquids: binary mixtures.
abstract: The phase behaviour of binary mixtures of ionic surfactants (1-alkyl-3-imidazolium chloride, C(n)mimCl with n=14, 16 and 18) and imidazolium-based ionic liquids (1-alkyl-3-methylimidazolium tetrachloroferrate, C(n)mimFeCl4, with n=2 and 4) over a broad temperature range and the complete range of compositions is described. By using many complementary methods including differential scanning calorimetry (DSC), polarised microscopy, small-angle neutron and X-ray scattering (SANS/SAXS), and surface tension, the ability of this model system to support self-assembly is described quantitatively and this behaviour is compared with common water systems. The existence of micelles swollen by the solvent can be deduced from SANS experiments and represent a possible model for aggregates, which has barely been considered for ionic-liquid systems until now, and can be ascribed to the rather low solvophobicity of the surfactants. Our investigation shows that, in general, C(n)mimCl is a rather weak amphiphile in these ionic liquids. The amphiphilic strength increases systematically with the length of the alkyl chain, as seen from the phase behaviour, the critical micelle concentration, and also the level of definition of the aggregates formed.
authors.affiliation: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Straße des 17. Juni 124, Sekr. TC7, Technische Universität Berlin, 10623 Berlin (Germany). andreas.klee@campus.tu-berlin.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Klee
authors.forename: Sylvain
authors.initials: S
authors.lastname: Prevost
authors.forename: Michael
authors.initials: M
authors.lastname: Gradzielski
mesh_terms: D003102:Colloids / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry; D060328:Magnetic Phenomena; D008823:Micelles; D044367:Phase Transition; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature
chemical_list: D003102:Colloids; D007093:Imidazoles; D052578:Ionic Liquids; D058085:Iron Compounds; D008823:Micelles; D013501:Surface-Active Agents; C029899:imidazole
keywords: colloids; ionic liquids; micelles; self-assembly; surfactants