Understanding the chain length dependence of thermal conductivity of liquid alcohols at 298 K on the basis of molecular-scale energy transfer

Many of the specifics of microscopic energy transfer in liquids are not sufficiently understood in spite of their importance in controlling heat transport in practical devices. The present study aims to clarify the details of microscopic energy transfer in associated liquids with the aid of non-equilibrium molecular dynamics (NEMD) simulations on the liquids of linear alcohols from ranging ethanol to decanol at normal conditions. The NEMD simulations reasonably reproduce the experimentally observed chain length dependence of thermal conductivity. The microscopic energy transfer corresponding to each type of interatomic interactions are analyzed in relation to the liquid structures and molecular morphologies. Our analysis shows that the heat transfer by the Coulomb interaction has only a limited contribution to the alcohol thermal conductivity. Molecular morphology also has little effect. Rather, the chain length dependence of the thermal conductivity is determined by the result of the competition between the intermolecular and intramolecular energy transfers. The new insights obtained in the present study are a step towards a molecular theory of the thermal conductivity of liquids.