Influence of salt on interaction between imidazolium based ionic liquid [C12mim][Br] and anionic polyelectrolyte poly(sodium-4-styrenesulfonate)

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 [C12mim][Br] in aqueous media has been investigated by isothermal calorimetry, surface tension, fluorescence and 1H NMR spectra. It was observed that the [C12mim][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 [C12mim][Br] and NaPSS above the critical aggregate surfactant concentration. But at high concentration of NaBr there is no [C12mim][Br]-NaPSS complex formation because of complete salt screening of the electrostatic attraction between NaPSS chains and the [C12mim][Br] micelles. A range of surface parameters akin as surface excess concentration (Γcmc), surface pressure at the interface (Πcmc), minimum area occupied by single SAIL molecule at air-solvent interface (Αmin), the adsorption efficiency (pC20) and surface tension at critical micelle concentration (cmc) (γcmc) are calculated from surface tension measurement for both with and without NaBr. The aggregation number (Nagg) 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 [C12mim][Br] in 0.010 g/L NaPSS also have been investigated through 1H NMR spectra.