Polarization of ethanol under thermal fields

Abstract

Thermal fields induce thermal polarization and the buildup of a stationary net electric field in polar liquids. While the thermal polarization effect in water has been studied before, the coupling effects between heat and polarization fluxes remain unexplored in most polar fluids. Here, we investigate thermal transport and thermal polarization in liquid and supercritical ethanol through non-equilibrium molecular dynamics simulations using the TraPPE force field. We discuss the thermal conductivity of ethanol under various thermodynamic conditions and its correlation with other thermophysical properties, such as isothermal compressibility and specific heat capacity. Furthermore, we demonstrate that thermal gradients polarize liquid and supercritical ethanol. We report an inversion in the sign of the polarization field along the liquid branch of the liquid–vapor saturation line and discuss the microscopic origin of this inversion. Near the critical point, the thermal polarization effect increases significantly, as observed in water. Finally, we show a correlation between the sign reversal of the thermal polarization and the minimum in the liquid–vapor surface potential of ethanol.