Highly Ordered BN ⊥ –BN ⊥ Stacking Structure for Improved Thermally Conductive Polymer Composites

The substantial heat generation in modern electronic devices is one of the major issues requiring efficient thermal management. This work demonstrates a novel concept for the design of thermally conducting networks inside a polymer matrix for the development of highly thermally conductive composites. Highly ordered hexagonal boron nitride (hBN) structures are obtained utilizing a freeze‐casting method. These structures are then thermally sintered to get a continuous network of BN ⊥ –BN ⊥ of high thermal conductivity in which a polymer matrix can be impregnated, enabling a directional and thermally conducting composite. The highest achieved thermal conductivity ( K ) is 4.38 W m −1 K −1 with a BN loading of 32 vol%. The effect of sintering temperatures on the K of the composite is investigated to optimize connectivity and thermal pathways while maintaining an open structure (porosity ≈ 2.7%). The composites also maintain good electrical insulation (volume resistivity ≈ 10 14  Ω cm). This new approach of thermally sintering BN ⊥ –BN ⊥ aligned structures opens up a new avenue for the design and preparation of filler alignment in polymer‐based composites for improving the thermal conductivity while maintaining high electrical resistance, which is a topic of interest in electronic packaging and power electronics applications.