Tuning the thermal conductivity of polymers with mechanical strains

The low thermal conductivity of polymers limits their heat spreading capability, which is one of the major technical barriers for the polymer-based products, especially electronics, such as organic light emitting diodes. It is highly desirable to enhance the thermal conductivity of polymer materials including polymer composites. Mechanical stretching could align polymer chains which are intrinsically low-dimensional material that could have very high thermal conductivity and thus enhancing the thermal conductivity of polymers. In this work, the all-atom model molecular-dynamics simulation is conducted to investigate the tuning of polymer thermal conductivity using mechanical strains. The simulation results show that the thermal conductivity of polymers increases with the increasing strain and the enhancement is larger when the polymer is stretched slower. Molecular weight also affects the thermal conductivity under the same stretching condition. More importantly, the thermal-conductivity enhancement could be exponentially fitted with the orientational order parameter which describes the chain conformation change. This study could guide the development of advanced reconfigurable and tunable thermal management technologies.