Effect of alkyl chain on micellisation properties of dodecylsulphate based surface active ionic liquids in aqueous solutions using conductance and surface tension techniques

Two surface active ionic liquids (ILs) having 1-alkyl-3-methylimidazolium cationic moiety and dodecylsulphate based anionic moiety, i.e. [C(5)mim][DS] and [C(7)mim][DS], have been synthesised. H-1-NMR, thin layer chromatography was done for their characterisation. The electrical conductivity and surface tension measurements were performed to investigate the interfacial and bulk properties of the aqueous solutions of different alkyl chain ionic liquids. These techniques were employed to study the aggregation behaviour in aqueous conditions. Various surface active parameters were evaluated at 298.15 K from the surface tension measurements. The lowest surface tension (.) and maximum surface excess concentration () values showed that [C(7)mim][DS] had the highest surface activity. Conductance measurements were performed at three rising temperatures (288.15, 298.15, and 308.15) K, and their thermodynamic parameters were calculated. It indicated that micellisation of both ionic liquids was entropy driven at all temperatures.