The effect of hydrophilic ionic liquid 1-butyl-2,3-dimethylimidazolium bromide on the aggregation behavior of tetradecyltrimethylammonium bromide in aqueous media

The aggregation behavior of a conventional cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), in a trisubstituted imidazolium based hydrophilic ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium bromide [bdmim][Br]/water systems was investigated by conductance, fluorescence, H-1 NMR spectroscopy and dynamic light scattering (DLS). Different physicochemical properties such as the critical micelle concentration (cmc), degree of dissociation (alpha), thermodynamic parameters (Delta G(m)degrees, Delta H-m degrees and Delta S-m degrees) of micellization, aggregation number (N-agg) and aggregate size were determined. The micelles formed just like in aqueous medium and cmc values were found to be smaller at different wt.% of IL than in water. The cmc value of TTAB gets lowered until 20.0 wt.% of IL in the medium. At significantly higher wt.% of IL in the system cmc becomes higher. The variation of chemical shifts of surfactant protons in the presence of IL revealed that the electrostatic interaction has a prominent influence on the cmc and other thermodynamic properties of surfactant. It is demonstrated that [bdmim][Br] can be judiciously utilized at different wt.% for enhancing the surface activity and altering the physicochemical properties of TTAB. (c) 2015 Elsevier B.V. All rights reserved.