Oriented BN/Silicone rubber composite thermal interface materials with high out-of-plane thermal conductivity and flexibility

Polymer composites with high out-of-plane thermal conductivity, flexibility, and low modulus have always been one of the ideal thermal interface materials. Using softer polymer composites can reduce thermal contact resistance and stress caused by the mismatch of the coefficient of thermal expansion, as well as heat can be quickly transferred due to its high out-of-plane thermal conductivity. Herein, we report a silicone rubber-based composites with high out-of-plane thermal conductivity and softness prepared by combining shear orientation and layer-by-layer stacking methods. The composites exhibit an out-of-plane thermal conductivity of 7.62 Wm(-1) K-1, while maintain the flexibility and high elastic recovery of silicone rubber. According to finite element simulation analysis, the increase in thermal conductivity comes from the orientation of the BN flakes and the formation of the thermal network. This work provides a simple method for the preparation of flexible thermal interface materials with high out-of-plane thermal conductivity for many potential applications.