Molecular dynamics simulation of the formation mechanism of the thermal conductive filler network of polymer nanocomposites

In this work, the thermal transfer capabilities of spherical and laminar/spherical filled polymer nanocomposites (PNCs) were systematically investigated by using molecular dynamics (MD) simulation. The effects of various factors such as physical interfacial interaction, filler size and filler shape on the thermal conductivity were explored. The relationship between thermal conductivity and its corresponding microstructure was examined. The thermal transfer ability of the PNCs was characterized using two approaches, including thermal conductivity (TC) and the filler conductive network. Our results showed that the increase in the filling fraction and the matrix-filler physical interfacial interaction were both conducive to the formation of the thermally conductive network. The non-linear effect of the filler size on the TC results from a competition between the filler overlapped structure and the physical interfacial interaction. Besides, the introduction of spherical nanoparticles (NPs) into laminar-filled PNCs and increasing the NP-polymer physical interfacial strength could remarkably promote the formation of a hybrid overlapping filler network and also a thermal conduction pathway. Moreover, the oscillatory shear could significantly increase the thermal conductivity of laminar/spherical filled PNCs by enhancing the overlapped structure between spherical fillers. This study provides some insights on understanding the relationship between the microstructures and the thermal conductivity of laminar/spherical NP filled PNCs at the molecular level.