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

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.