فرخنده مظفری

The reverse nonequilibrium molecular dynamics simulation technique has been applied to study the thermal conductivity of polyamide-6,6 (100 chemical repeat units), in contact with, on one side graphene, and vacuum on the other side. For this purpose equilibrium molecular dynamics simulations are performed in isothermal- isobaric ensemble. To calculate the thermal conductivity of nanoconfined polymer the simulation box, is divided into several slabs along the direction of heat flow. The heat transfer is done in an artificial, nonphysical manner between graphene surface and a polymer layer at the vacuum interface. At the steady state the thermal conductivity is calculated from the amount of energy transferred and the response of the system to the perturbation. The results of this study show that the thermal conductivity in the pore, with respect to the bulk polymer, decreases. Very close to the graphene interface, the chains adopt flatten conformations, restricting the heat transfer via molecular collisions. The coefficient of thermal conductivity converges to the corresponding bulk value at distances as long as 5 nm from the graphene surface. At the vacuum interface, however the thermal conductivity is larger than the corresponding bulk value. This is due to higher mobility of the chains in this interface.