Reverse nonequilibrium molecular dynamics simulation of thermal conductivity in nanoconfined polyamide-6,6

Abstract

A new molecular dynamics simulation method, with coupling to external baths, is used to perform equilibrium simulations on polyamide-6,6 trimers nanoconfined between graphene surfaces, in equilibrium with the bulk polymer. The method is coupled with the reverse nonequilibrium molecular dynamics simulation technique to exchange heat in the direction normal to the surfaces. To be able to study the effect of confinement on the heat conductance in nanoconfined pores, in this work a number of simulations on systems with different pore sizes are done. It is concluded that the coefficient of heat conductivity depends on the degree of polymer layering between the surfaces and on the pore width. Our results further indicate a considerable temperature drop at the interface between the surfaces and polymer. The calculated Kapitza lengths depend on the intersurface distance and on the layering of the polymer nanoconfined between the surfaces.

Anisotropic heat transport in nanoconfined polyamide-6,6 oligomers: Atomistic reverse nonequilibrium molecular dynamics simulation

“…In a previous study we have employed this method to study the heat transfer across the pore. 22 Our results indicated that a substantial temperature drop is observed at the interface. Resultantly, the coefficient of thermal conductivity in the perpendicular direction, depending on the pore width, is shown to be smaller than the corresponding bulk value.…”

“…[20][21][22] We have shown that the heat flow across the pore occurs much slower than that in the bulk polymer. 22 In this work we will examine the heat flow in the direction parallel to the surfaces, by coupling our NAPT ensemble simulation method with the RNEMD technique [23][24][25] to study the anisotropic heat flow in naoconfined polymers. Same as the previous work, our polymeric system is a sample of polyamide-6,6 oligomers (the chemical structure is shown in Fig.…”

“…Resultantly, the coefficient of thermal conductivity in the perpendicular direction, depending on the pore width, is shown to be smaller than the corresponding bulk value. 22 In this work, we aim to apply the above cited method to study the heat flow parallel to the surfaces and compare the results with the bulk sample and with our previous results on the heat flow in the perpendicular direction.…”

“…19 As a continuation of our previous works 20-22 on the equilibrium and transport properties of nanoconfined polyamide-6,6, in this work we perform reverse nonequilibrium molecular dynamics (RNEMD) simulation [23][24][25] to study the anisotropic heat flow in confined polyamide-6,6 between graphene surfaces. We have shown in our previous work 22 that the heat flow in the perpendicular (to the surfaces) direction depends on the pore width. In this case considerable decrease in the heat conduction, with respect to the bulk polymer, occurs due to the temperature drop at the interface between polymer and graphene surfaces.…”

Recent Advances in Graphene-Based Free-Standing Films for Thermal Management: Synthesis, Properties, and Applications

“…This may be due to the ultralow thermal conductivity of the polymer (~0.1 W/m·K) compared to that of graphene (>100 W/m·K), transforming the ballistic heat transfer in graphene to the diffusive heat transfer in polymers [76,77]. Moreover, a number of theoretical studies have demonstrated that the interfacial thermal resistance (often known as the Kapitza resistance) between graphene and polymer also lowers the thermal conductivity of the composite films [78][79][80][81].…”