A comparative study on the effect of imidazolium-based ionic liquid on self-aggregation of cationic, anionic and nonionic surfactants studied by surface tension, conductivity, fluorescence and FTIR spectroscopy

The surfactants aggregation morphology may be modified by varying the choice of suitable ionic liquids. The aggregation behavior of cetyltrimethylammonium bromide (CTAB), sodium dodecylsulphate (SDS) and polyoxyethylene lauryl ether (Brij-35) have been investigated in the presence of 1-ethyl-3-methylimidazolium bromide[Emim][Br]. The effect of [Emim][Br] was also studied on the micellization of 1-butyl-3-methylimidazolium octylsulphate [Bmim][OS] in comparison to other surfactants. Various interfacial properties and thermodynamic parameters were determined by the surface tension and conductivity method. The local microenvironment (I-1/I-3), the aggregation number (N-agg) and Stern Volmer constant (K-sv) were also obtained from steady-state fluorescence quenching method. Analysis of tensiometry and conductivity data were suggested and confirmed by fluorescence results. The micellization behavior of surfactants sytems were studied from the stretching vibrational bands between 400 and 2800 cm(-1) by FTIR spectroscopy. It has been observed that the CMC values of all surfactants systems decrease with [Emim] [Br]. Among all the surfactants, micellization of SDS was significantly influenced by [Emim][Br] due to the reason that the sulphate ion of SDS shows stronger electrostatic interaction with imidazolium cation of [Emim][Br]. (C) 2017 Published by Elsevier B.V.