Bi-directional high thermal conductive epoxy composites with radially aligned boron nitride nanosheets lamellae

Hexagonal boron nitride (h-BN), as a high thermal conductive filler, has been widely used to construct thermal transport network in polymers. However, anisotropic thermal property of BN and its conventional thermal conductive network usually lead to high thermal conductivity in one direction that limits the overall heat dissipation effect. Herein, we report a novel radially aligned three-dimensional boron nitride nanosheets/epoxy composite for thermal interface materials via radial freeze-casting method. The as-prepared composite with radially aligned boron nitride nanosheets lamellae exhibits bidirectional high thermal conductivity, with 4.02 W m(-1) K-1 in the through-plane direction and 3.87 W m(-1) K-1 in the in-plane direction even at low BNNS loading (e.g., 15 vol%), respectively. Besides, excellent electronic insulation property and shape stability can also meet the requirements of isotropic TIM in thermal management.