Controllable exfoliation of hexagonal boron nitride and tailored three‐dimensional network for highly thermally conductive polymer composites

Abstract Thermally conductive but electrically insulating composites have become significant components for efficient thermal dissipation in electronic devices due to their miniaturization, integration, and functionalization. Over the past decade, extensive efforts have been dedicated to improving the thermal conductivity of polymer‐based composites through incorporating various thermally conductive fillers. In particular, boron nitride nanosheets (BNNS) with outstanding intrinsic thermal conductivity, electrical insulation, and chemical stability, have sparked intensive interest from researchers. However, BNNS usually suffers from severe aggregation in polymer matrices, leading to high interfacial thermal resistance. Rational construction of three‐dimensional (3D) BNNS continuous networks is crucial for efficient thermal transport and has also been established as a feasible and effective approach to achieve significant enhancement of thermal conductivity for polymer/BNNS composites. In this brief review, we summarized and introduced recent progress on the controllable exfoliation of h‐BN and tailored three‐dimensional networks for highly thermally conductive polymer composites. The fabrication strategies for 3D BNNS networks and the structure–properties relationships of polymer/BNNS composites are highlighted. Finally, the opportunities and challenges for polymer/BNNS composites based on 3D thermally conductive networks are prospected.