title: Self-assembly of new surface active ionic liquids based on Aerosol-OT in aqueous media.
abstract: 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.
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Central Salt and Marine Chemicals Research Institute, Council of Scientific & Industrial Research (CSIR), G.B. Marg, Bhavnagar 364002, Gujarat, India.
authors.forename: K Srinivasa
authors.initials: KS
authors.lastname: Rao
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Central Salt and Marine Chemicals Research Institute, Council of Scientific & Industrial Research (CSIR), G.B. Marg, Bhavnagar 364002, Gujarat, India.
authors.forename: Praveen Singh
authors.initials: PS
authors.lastname: Gehlot
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Central Salt and Marine Chemicals Research Institute, Council of Scientific & Industrial Research (CSIR), G.B. Marg, Bhavnagar 364002, Gujarat, India.
authors.forename: Tushar J
authors.initials: TJ
authors.lastname: Trivedi
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Central Salt and Marine Chemicals Research Institute, Council of Scientific & Industrial Research (CSIR), G.B. Marg, Bhavnagar 364002, Gujarat, India; Salt & Marine Chemicals Division, Central Salt and Marine Chemicals Research Institute, Council of Scientific & Industrial Research (CSIR), G.B. Marg, Bhavnagar 364002, Gujarat, India. Electronic address: mailme_arvind@yahoo.com.
authors.forename: Arvind
authors.initials: A
authors.lastname: Kumar
keywords: Aerosol-OT; Counterion; Hydrophobic ionic liquid; Isothermal titration calorimtry; SAIL; Surface active ionic liquid; Surfactant solubility; Vesicle