Thermal percolation and electrical insulation in composite materials with partially metallic coated fillers

We propose a type of thermal interface materials incorporating insulating nanowires with partially metallic coating in insulating polymer matrix.Large thermal conductivity can be obtained due to thermal percolation while the electrical insulation is maintained by controlling $C_{\rm M}\varphi < \varphi_{\rm c}^{\rm e}$ and $\varphi > \varphi_{\rm c}^{\rm th}$, where $\varphi$ is the volume fraction of filler, $C_{\rm M}$ is the metallic coating fraction, $\varphi_{\rm c}^{\rm e}$ and $\varphi_{\rm c}^{\rm th}$ are the electrical and thermal percolation thresholds, respectively. The electrical conductivity of such composite materials can further be regulated by coating configuration. In this regard, we propose the concept of "thermal-percolation electrical-insulation", providing a guide to design efficient hybrid thermal interface materials.