Effects of electrostatic interactions on Kapitza resistance in hexagonal boron nitride-water interfaces

TL;DR

This study uses molecular dynamics simulations to explore how electrostatic interactions affect the Kapitza resistance at hexagonal boron nitride-water interfaces, revealing effects of nanotube diameter, partial charges, salt, and electric fields.

Contribution

It provides new insights into how electrostatic factors influence interfacial thermal resistance in hBN-water systems, including effects of charge, salt, and electric fields.

Findings

Kapitza resistance decreases with nanotube diameter due to water aggregation.

Higher partial charges on boron and nitrogen reduce $R_k$ via enhanced hydrogen bonding.

Salt concentration does not significantly affect interfacial thermal transport.

Abstract

Electrostatic interactions in nanoscale systems can influence the heat transfer mechanism and interfacial properties. This study uses molecular dynamics simulations to investigate the impact of various electrostatic interactions on the Kapitza resistance ($R_k$) on a hexagonal boron nitride-water system. The Kapitza resistance at hexagonal boron nitride nanotube (hBNNT)-water interface reduces with an increase in diameter of the nanotube due to more aggregation of water molecules per unit surface area. An increase in the partial charges on boron and nitride caused the reduction in $R_k$. With the increase in partial charge, a better hydrogen bonding between hBNNT and water was observed, whereas the structure and order of the water molecules remain the same. Nevertheless, the addition of NaCl salt into water does not have any influence on interfacial thermal transport. $R_k$ remains unchanged with electrolyte concentration since the cumulative Coulombic interaction between the ions, and the hBNNT is significantly less when compared with water molecules. Furthermore, the effect of electric field strength on interfacial heat transfer is also investigated by providing uniform positive and negative surface charges on the outermost hBN layers. $R_k$ is nearly independent of the practical range of applied electric fields and decreases with an increasing electric field for extreme field strengths until the electro-freezing phenomenon occurs. The ordering of water molecules towards the charged surface leads to an increase in the layering effect, causing the reduction in $R_k$ in the presence of an electric field.