Influence of salt on interaction between imidazolium based ionic liquid [C 12 mim][Br] and anionic polyelectrolyte poly(sodium-4-styrenesulfonate)

Abstract

Abstract The influence of alkali salt [NaBr] on complex formation between anionic polyelectrolyte poly(sodium-4-styrenesulfonate) [NaPSS] and surface active ionic liquid (SAIL) 1-dodecyl-3-methylimidazolium bromide [C 12 mim][Br] in aqueous media has been investigated by isothermal calorimetry, surface tension, fluorescence and 1 H NMR spectra. It was observed that the [C 12 mim][Br]-NaPSS complexes were effected markedly with the increased addition of salt. At lower concentration, NaBr smooth the path of formation of micelle-like aggregates between [C 12 mim][Br] and NaPSS above the critical aggregate surfactant concentration. But at high concentration of NaBr there is no [C 12 mim][Br]-NaPSS complex formation because of complete salt screening of the electrostatic attraction between NaPSS chains and the [C 12 mim][Br] micelles. A range of surface parameters akin as surface excess concentration (Γ cmc ), surface pressure at the interface (Π cmc ), minimum area occupied by single SAIL molecule at air-solvent interface (Α min ), the adsorption efficiency (pC 20 ) and surface tension at critical micelle concentration (cmc) ( γ cmc ) are calculated from surface tension measurement for both with and without NaBr. The aggregation number (N agg ) and cmc is also derived from fluorescence probe behavior and cmc obtained from all above techniques are in proper consent with each other. The interpretation of various inter-molecular interactions amid NaBr and molecules of [C 12 mim][Br] in 0.010 g/L NaPSS also have been investigated through 1 H NMR spectra.