Nanoconfinement Effects on the Kapitza Resistance at Water–CNT Interfaces

Abstract

The Kapitza resistance (R k ) at the water−carbon nanotube (CNT) interface, with water on the inside of the nanotube, was investigated using molecular dynamics simulations. We propose a new equilibrium molecular dynamics (EMD) method, also valid in the weak flow regime, to determine the Kapitza resistance in a cylindrical nanoconfinement system where nonequilibrium molecular dynamics (NEMD) methods are not suitable. The proposed method is independent of the correlation time compared to Green−Kubo-based methods, which only work in short correlation time intervals. R k between the CNT and the confined water strongly depends on the diameter of the nanotube and is found to decrease with an increase in the CNT diameter, the opposite to what is reported in the literature when water is on the outside of the nanotube. R k is furthermore found to converge to the planar graphene surface value as the number of water molecules per unit surface area approaches the value in the graphene surface and a higher overlap of the vibrational spectrum. A slight increase in R k with the addition of the number of CNT walls was observed, whereas the chirality and flow do not have any impact.

An atomistic model for the thermal resistance of a liquid–solid interface

“…The TSWF, the primary factor affecting variations in the value of the resistance, is essentially a measure of the strength of interaction between the wall and fluid; a reduced interaction increases the thermal resistance and vice versa. This insight can be used to explain the recent observations (Alosious et al 2021) on the dependence of R K on nanotube curvature and number of wall layers. The thermal relaxation time, or at least its approximation by κ/DM ∞ , is a property of the fluid only.…”

An atomistic model for the thermal resistance of a liquid-solid interface

“…The TSWF, the primary factor affecting variations in the value of the resistance, is essentially a measure of the strength of interaction between the wall and fluid; a reduced interaction increases the thermal resistance and vice versa. This insight can be used to explain the recent observations [24] on the dependence of R K on nanotube curvature and number of wall layers. The thermal relaxation time, or at least its approximation by κ/DM ∞ , is a property of the fluid only.…”

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

“…The detailed derivation of the theory is available in the original paper. 30 The Kapitza resistance or the interfacial thermal resistance, R k is defined as…”

“…51 The fluid slab thickness, ∆ was taken as 3.165 Å, which is the distance measured from the wall to the first density peak of water. 30,31 All the calculated parameters were averaged over five independent simulations with distinct initial configurations.…”

“…The effect of hBNNT partial charge, electrolyte concentration and electric field were analyzed in cylindrical and planar hBN-water systems. The Kapitza resistance/length calculations were carried out using our previously developed EMD method 30 since the NEMD method is unsuitable for the cylindrical system used in this study. The Kapitza resistance is found to be decreasing with an increase in partial charge of hBNNT and applied electric field, whereas the increase in molarity of the NaCl electrolyte does not make any impact.…”