Influence of Molecular Structure on Densities and Viscosities of Several Ionic Liquids

Abstract

One of the potential applications of the ionic liquids (ILs) is their use as lubricants or lubricant additives. The choice of the cation and the anion of the ILs, as well as the side chain design, determine their fundamental properties, which permits us to create tailor-made lubricants and lubricant additives among other functional fluids. In this work we have studied 10 ILs for which we report densities and viscosities from 283.15 K (and for some ILs at lower temperatures) up to 373.15 K. The viscosities of the ILs fall in the range of the applications of hydraulic fluid or lubricants. Four of these ILs were composed by the anion tris(pentafluoroethyl)trifluorophosphate [(C 2 F 5 ) 3 PF 3 ] À and one of the following cations:and trihexyl(tetradecyl)phosphonium [P 6,6,6,14 ] + . Furthermore, three of the ILs contain the anion bis(trifloromethylsulfonyl)imide [NTf 2 ] À and one of the following cations [C 4 C 1 C 1 mim] + , [C 4 C 1 Pyrr] + , or [C 1 OC 2 C 1 Pyrr] + . Two other ILs contain the 1-ethyl-3-methylimidazolium cation [C 2 C 1 mim] + and an alkyl sulfate anion (ethylsulfate [C 2 SO 4 ] À or n-hexylsulfate [C 6 SO 4 ] À ). The last one is composed by [C 4 C 1 Pyrr] + and trifluoromethanesulfonate [CF 3 SO 3 ] À . The experimental values were used to determine the glass-transition temperature and fragility of these ILs and to analyze the capability of two group contribution methods recently proposed by Gardas and Coutinho for the density and viscosity prediction of ILs.

High Pressure Rheological Behavior of 1-Ethyl-3-methylimidazolium n-Hexylsulfate and Trihexyl(tetradecyl)phosphonium Tris(pentafluoroethyl)trifluorophosphate

“…A Newtonian behaviour was found for the studied ILs in the temperature, pressure and shear rate ranges analysed in this work. The reference viscosity values at atmospheric pressure employed for calibration were taken from Gaciño et al 37 and the obtained viscosity values at high pressure are presented in 60 correlation, for which those viscosity data at atmospheric pressure from Gaciño et al 37 were also employed:…”

“…The parameters A, B and C were obtained from the correlation of previously reported viscosity values 37 63 , AAD% in the whole experimental temperature and pressure range is 11%, whereas the maximum difference is 30%.…”

“…There are several works that study the viscous behavior at constant shear rate with falling body viscometers [30][31][32] , rotational viscometers [33][34][35][36][37] , rolling ball viscometers 38 , capillary viscometers 39 and vibrating wire viscometers 40 , among others. Concerning rheological studies at not constant shear rates, there are only some publications at atmospheric pressure.…”

New quantum chemistry-based descriptors for better prediction of melting point and viscosity of ionic liquids

“…[46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] Once more, a multivariate correlation with several quantum chemistry descriptors along with temperature as input parameters, and ln (viscosity), as the output parameter, was developed using Eureqa software.…”

Group Contribution Methods for Estimation of Selected Physico-Chemical Properties of Organic Compounds

“…for density, thermal expansion and viscosity of cholinium-derived ionic liquids (Costa et al, 2011;Costa et al, 2012), viscosity (Adamová et al, 2011, the glass-transition temperature and fragility (Gacino et al, 2011), experimental data of mixture with ionic liquid were compared with group contribution methods (Cehreli & Gmehling, 2010) or thermophysical properties were studied (Gardas et al, 2010).…”