Measurements of the density, refractive index, electrical conductivity, thermal conductivity and dynamic viscosity for tributylmethylphosphonium and methylsulfate based ionic liquids

• Published in: Thermochimica acta 2018-06, Vol.664, p.81-90
• Main Authors: Rodil, Eva, Arce, Alberto, Soto, Ana
• Format: Article
• Language: English
• Subjects: Ionic liquids; Temperature dependence; Thermal stability; Thermophysical properties
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2018.04.007

[Display omitted] •Tributylmethylphosphonium and Methylsulfate based ILs were synthesized.•The structures of the ionic liquids were characterized by 1H NMR, 13C NMR and TGA.•Several thermophysical properties of ILs were measured as function of temperature.•Effects of temperature and ions on thermophysical properties were investigated. In this work, the effect of ion and temperature change on the thermophysical properties of several ionic liquids was investigated. Five room-temperature ionic-liquids were selected: tributylmethylphosphonium chloride ([P4441]Cl), tributylmethylphosphonium bis(trifluoromethylsulfonyl) amide ([P4441][NTf2]), tributylmethylphosphonium methylsulfate ([P4441][MeSO4]), 1-methylpyridinium methylsulfate ([C1py][MeSO4]), and 1-butyl-3-methylimidazolium methylsulfate ([C4mim][MeSO4]). Densities, refractive indices, electrical conductivities, thermal conductivities and dynamic viscosities were reported ranging from (283.15 to 343.15) K at atmospheric pressure. The thermal stability of all the ionic liquids has been also studied at a heating rate of 5 K min−1 using a thermogravimetric analyzer. The effect of temperature change on density was discussed in terms of ion volume, and the influence on electrical conductivity and dynamic viscosity was discussed in terms of ion mobility. The effect of the variation of the ion was discussed in terms of size, steric effects and interaction strength between cation and anion. Finally, the temperature dependence for density, refractive index and thermal conductivity was correlated with linear functions, while a Vogel-Fulcher-Tammann type function was used for the correlation of the temperature dependence for electrical conductivity and dynamic viscosity.