TY - JOUR
T1 - Thermophysical properties of [CN − 1C1im][PF6] ionic liquids
AU - Alves da Rocha, M.A.
AU - Ribeiro, F.M.S.
AU - Lobo Ferreira, A.I.M.C.
AU - Coutinho, J.A.P.
AU - Santos, L.M.N.B.F.
PY - 2013
Y1 - 2013
N2 - Densities, viscosities and refractive index, as a function of temperature, and isobaric thermal expansion coefficient, were determined for 1-alkyl-3-methylimidazolium hexafluorophosphate, [CN − 1C1im][PF6] (where N = 5 to 10) series of ionic liquids. The density presents a regular decrease along the ionic liquid series, with no detectable alkyl chain length dependence of the thermal expansion coefficient. Both the refractive index and viscosity show a trend shift along the series around the [C6C1im][PF6] that could be associated to the impact of the change in the nanostructuration of the ionic liquids. The experimental results are compared with the analogous [CN − 1C1im][NTf2] series and the effect of the anion is analyzed. The sphericity of the [PF6]− anion is reflected in the lower pre-exponential VTF parameter, Aη, and the higher viscosity of the [CN − 1C1im][PF6], when compared with the [CN − 1C1im][NTf2] series, is ruled by the higher energy barriers, which are related with stronger electrostatic interaction due to the low charge dispersion of the [PF6]−.anion.
AB - Densities, viscosities and refractive index, as a function of temperature, and isobaric thermal expansion coefficient, were determined for 1-alkyl-3-methylimidazolium hexafluorophosphate, [CN − 1C1im][PF6] (where N = 5 to 10) series of ionic liquids. The density presents a regular decrease along the ionic liquid series, with no detectable alkyl chain length dependence of the thermal expansion coefficient. Both the refractive index and viscosity show a trend shift along the series around the [C6C1im][PF6] that could be associated to the impact of the change in the nanostructuration of the ionic liquids. The experimental results are compared with the analogous [CN − 1C1im][NTf2] series and the effect of the anion is analyzed. The sphericity of the [PF6]− anion is reflected in the lower pre-exponential VTF parameter, Aη, and the higher viscosity of the [CN − 1C1im][PF6], when compared with the [CN − 1C1im][NTf2] series, is ruled by the higher energy barriers, which are related with stronger electrostatic interaction due to the low charge dispersion of the [PF6]−.anion.
U2 - 10.1016/j.molliq.2013.09.031
DO - 10.1016/j.molliq.2013.09.031
M3 - Article
SN - 0167-7322
VL - 188
SP - 196
EP - 202
JO - Journal of Molecular Liquids
JF - Journal of Molecular Liquids
ER -