Imidazolium‐Based Ionic Liquid as Modulator of Physicochemical Properties of Cationic, Anionic, Nonionic, and Gemini Surfactants.

Abstract: The aggregation morphology of 2 cationic surfactants (cetyldimethylethanolammonium bromide and cetyldiethylethanolammonium bromide), an anionic surfactant (sodium dodecylbenzenesulfonate), a nonionic surfactant (Triton X‐100), and 2 gemini surfactants (16‐4‐16,2Br⁻[butanediyi‐1,4‐bis(dimethyldohexylammonium bromide)] and 16‐6‐16,2Br⁻[hexanediyi‐1,6‐bis(dimethyldohexylammonium bromide)]) in the presence of the ionic liquid (IL) 1‐ethyl‐3‐methylimidazoliumbromide [Emim][Br] is studied using various techniques such as surface tension, conductivity, and UV–visible and fluorescence spectroscopy. Increasing the concentration of [Emim][Br] results in a decrease in the critical micelle concentration (CMC) value of the surfactants. Various interfacial properties, namely the surface excess concentration (Г_max), minimum area per molecule at the air–water interface (<italic>A</italic>_min)_, and surface pressure at the CMC (<italic>π</italic>_cmc), as well as the thermodynamic parameters such as free energy of the given air/water interface ( G min s), Gibbs free energy of micelle formation ( Δ G m °), Gibbs free energy of micellization per alkyl tail ( Δ G m , tail °), Gibbs energy of transfer ( Δ G trans °), and standard free energy of adsorption ( Δ G ads °) were also investigated. The aggregation number (<italic>N</italic>_agg) was determined by the fluorescence method. It was observed that <italic>N</italic>_agg decreased with increasing weight‐percent of the IL. [ABSTRACT FROM AUTHOR]