Interactions of Sodium Polystyrene Sulfonate with 1-Octyl-3-methylimidazolium Bromide in Aqueous Solution: Conductometric, Spectroscopic and Density Functional Theory Studies

Abstract

Conductivity measurements were performed for aqueous mixtures of sodium polystyrene sulfonate (NaPSS) and 1-octyl-3-methylimidazolium bromide ([OMIm]Br) at 288.15, 298.15 and 308.15 K. Scaling theory is used for the description of the electrical conductance of the polyelectrolytes. The results indicate that the fraction of uncondensed counterions is decreased by increasing the temperature or concentration of [OMIm]Br. Conductivity measurements for 1-octyl-3-methylimidazolium bromide were performed in aqueous solutions of sodium polystyrene sulfonate. Data analysis was performed using the Quint–Viallard conductivity equation and the low concentration chemical model. Limiting molar conductivities of [OMIm]Br (Λ0) and the association constant (KA) were determined. The molar conductivity of [OMIm]Br in aqueous solutions of NaPSS increased with increasing temperature. Values of activation energy for viscous flow are higher than the values of activation enthalpy of charge transport; therefore, it can be concluded that, in addition to ion transfer, the formation and breaking of hydrogen bonds is responsible for a portion of the charge transfer. The results of UV–Vis spectroscopic and quantum chemical calculations confirmed the existence of hydrogen bonding between [OMIm]+ and [PSS]–.