Effect of a copolymer poly(4-styrenesufonic acid-co-maleic acid) sodium salt on aggregation behaviour of imidazolium based surface active ionic liquid in aqueous solution

Aim of the present investigation is to broaden an understanding of the interactions between imidazolium based cationic surface active ionic liquid (SAIL) 1-dodecyl-3-methylimidazolium bromide [C12mim][Br] and an anionic polyelectrolyte poly(4-styrenesufonic acid-co-maleic acid) sodium salt (PSSA-co-MA) in aqueous media by using fluorimetry, conductometry and tensiometry techniques. The various states of interaction and critical micelle concentration (cmc) have been reviewed due to the strong hydrophobic and electrostatic interactions. Also degree of ionization, α, cmc and various thermodynamic parameters were determined by conductivity measurement in the temperature range 298.15-318.15 K. The surface tension curve displays the presence of pronounced knap in the surface tension at SAIL concentrations below cmc of the SAIL. The various surface parameters are calculated from surface tension measurement. Aggregation number (Nagg) and cmc were determined by fluorimetric measurements at temperature 298 K. In all cases it was observed that the cmc values were decreased with increase in the concentration of polyelectrolyte this is attributed to the strong electrostatic interactions between SAIL and polyelectrolyte. Also the aggregation behaviour of SAIL begins shifting from entropy-driven to enthalpy-driven with increasing the concentration of polyelectrolyte and increase in temperature. The results obtained from different measurements are in good agreement with each other.