Changes in Permittivity and Density of Molecular Liquids under High Pressure

Abstract

We collected and analyzed the density and permittivity of 57 nonpolar and dipolar molecular liquids at different temperatures (143 sets) and pressures (555 sets). No equation was found that could accurately predict the change to polar liquid permittivity by the change of its density in the range of the pressures and temperatures tested. Consequently, the influence of high hydrostatic pressure and temperature on liquid permittivity may be a more complicated process compared to density changes. The pressure and temperature coefficients of permittivity can be drastically larger than the pressure and temperature coefficients of density, indicating that pressure and particularly temperature significantly affect the structure of molecular liquids. These changes have less influence on the density change but can strongly affect the permittivity change. The clear relationship between the tangent and secant moduli of the permittivity curvatures under pressure for various molecular liquids at different temperatures was obtained, from which one can calculate the Tait equation coefficients from the experimental values of the pressure influence on the permittivity at ambient pressure.

Influence of Temperature on the Liquid–Liquid Phase Equilibria of Ternary (Water + Alcohol + Entrainer) Systems

“…Relative dielectric constants, ε r (relative to the permittivity of a vacuum, ε o ), as functions of temperature on a semilog scale. The equations to plot ε r for all components except DIPE are taken from Wohlfarth; data for DIPE are taken from Kiselev et al …”

“…These observed trends can be explained through the component polarities, which are related to the intermolecular polar forces and solvation effects, both of which are important phenomena in the (water + alcohol + entrainer) systems investigated here. 17 The polarities of the components involved, in terms of their dielectric constants, 18,19 are shown in Figure 8 as functions of temperature. According to the like-dissolves-like rule, a solute (in this case the alcohol) will solvate more easily in a solvent (water or entrainer) of similar polarity.…”

Electrostriction of Several Nonaqueous Solvents under Ambient Conditions and Solvation Numbers of Ions in Them

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“…The pressure-dependent permittivity data for several solvents, 2-butanone, dichloroethanes, benzonitrile, and nitromethane, were obtained from Kiselev et al and fitted again to quadratic expressions for ln ε­( P ) T , with r corr 2 ≥ 0.999, except for 1,1-dichloroethane, for which r corr 2 = 0.9981. Although these authors related the permittivities to the densities, they did not provide direct data for the latter; thus, these were obtained from other sources.…”

Multiphase Behavior of Tetraphenylethylene Derivatives with Different Polarities at High Pressures

“…However, in contrast, we can study the effects of pressure over a wider range. The pressure dependence of the permittivity has been reported for various solvents such as water, 26 organic solvents, [27][28][29][30] and thallous halides. 31 We have previously reported that the fluorescence spectrum of a mechanochromic molecule shows a red-shift under high pressures because of the increase in the solvent polarity around the molecule.…”