| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 607230 | Journal of Colloid and Interface Science | 2014 | 9 Pages |
•Four new surface active ionic liquids have been synthesized.•All are derived from sodium dioctylsulfosuccinate by exchanging counterion.•All new surface active ionic liquids have shown improved surface activity.•These new surface active ionic liquids self-assembled into vesicles in aqueous solution.•The insolubility of anionic surfactants in hydrophobic ionic liquid medium is improved.
New anionic ionic liquid surfactants have been synthesized by replacing the sodium cation of Aerosol-OT (sodium dioctylsulfosuccinate, [Na]AOT) with various biocompatible moieties, such as 1-butyl-3-methyl imidazolium ([C4mim]), proliniumisopropylester ([ProC3]), cholinium ([Cho]), and guanidinium ([Gua]). The Aerosol-OT derived ionic liquids (AOT-ILs) were found fairly soluble in water and formed vesicles above a critical vesicle concentration (CVC) which depended upon the nature of cation, and followed the order: [ProC3] < [C4mim] < [Gua] < [Cho] < Na+. The self-assembly process was characterized using surface tension (ST), isothermal titration calorimetry (ITC), conductivity, dynamic light scattering (DLS), nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). Unlike other AOT-ILs, a structural transformation has been observed for [C4mim]AOT above CVC, because of certain amphiphilic character in the cation [C4mim]. Thermodynamic parameters calculated from ITC and conductivity techniques revealed that the vesicle formation process is entropy driven for [C4mim]AOT, whereas the process is both enthalpy and entropy driven for other AOT-ILs. In order to check the versatility of synthesized AOT-ILs we have tested their dissolution behavior in a different class of ionic liquids. All the AOT-ILs were found fairly soluble in the hydrophilic IL, ethanolammonium formate (EOAF), whereas only [C4mim]AOT and [ProC3]AOT were found soluble in hydrophobic IL, [C4mim]Tf2N. Such combinations can have potential for construction of stable colloidal formulations or microemulsions in ionic liquid media.
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