Temperature Dependence of Physicochemical Properties of Imidazolium-, Pyroldinium-, and Phosphonium-Based Ionic Liquids

Densities, viscosities, speeds of sound, surface tensions, and refractive indices for nine different imidazolium-, pyroldinium-, and phosphonium-based ionic liquids were measured at temperatures ranging from 298.15 K to 333.15 K and atmospheric pressure. Empirical models were used to correlate the thermophysical properties of the ionic liquids as a function of temperature. The isentropic compressibility, coefficients of thermal expansion, surface properties, and critical temperatures were calculated using the experimental data. Furthermore, the effect of anions and alkyl chains of the different ionic liquids on their thermophysical properties had been investigated.