title: Modifying effect of imidazolium-based ionic liquids on surface activity and self-assembled nanostructures of sodium dodecyl sulfate.
abstract: The effect of four cationic ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride (BMImCl), 1-butyl-3-methylimidazolium bromide (BMImBr), 1-hexyl-3-methylimidazolium chloride (HMImCl), and 1-hexyl-3-methyl-imidazolium bromide (HMImBr) on surface activity and micellization of an anionic surfactant, sodium dodecyl sulfate (SDS), is studied. The thermodynamic data on micellization and surface adsorption are obtained from tensiometry and conductometry. The applicability of UV-visible spectroscopy to study of SDS/IL systems is also investigated using Crystal Violet as the probe. Cyclic voltammetry, dynamic light scattering, and TEM imaging are employed to investigate the size and morphology of aggregates. According to the findings, addition of butyl-chained ILs to aqueous SDS results in only a slight gradual increase in average aggregate size whereas the size of SDS assemblies are dramatically increased upon addition of hexyl-chained ILs. It is proposed that BMIm(+) cations of the IL undergo Coulombic attractive interactions with anionic headgroups adsorbed at the micellar surface in aqueous SDS whereas HMIm(+) interact through hydrophobic chain-chain attractions as well. Thus, mixed micellization results in formation of vesicles. A micellar phase change from vesicles to micelles takes place at higher [SDS]/[IL] ratios. All of these processes are successfully tracked by the employed techniques.
authors.affiliation: Department of Chemistry, Faculty of Science, Tarbiat Modares University , P.O. Box 14115-175, Tehran, Iran.
authors.forename: Soheila
authors.initials: S
authors.lastname: Javadian
authors.forename: Fayezeh
authors.initials: F
authors.lastname: Nasiri
authors.forename: Akbar
authors.initials: A
authors.lastname: Heydari
authors.forename: Ali
authors.initials: A
authors.lastname: Yousefi
authors.forename: Afshin Asadzadeh
authors.initials: AA
authors.lastname: Shahir
mesh_terms: D000327:Adsorption; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D007093:Imidazoles; D052578:Ionic Liquids; D012967:Sodium Dodecyl Sulfate