Thermally conductive composites based on hexagonal boron nitride nanosheets for thermal management: Fundamentals to applications

The development of modern electronics and equipment, especially those with high power density, has long relied on rapid heat dissipation of integrated chips, yet a challenge to date. Thermally conductive fillers are a class of valuable materials for thermal management by combination of polymers, thus are widely utilized in this field. Hexagonal boron nitride nanosheet (h-BNNS) has high thermal conductivity, electrical insulation, structural stability, excellent mechanical property and other properties, making it one of the most promising thermally conductive fillers. This review aims to systematically summarize the research progress and application of h-BNNS as a thermally conductive filler. We begin with an introduction on the various preparation approaches of h-BNNS, followed by a discussion of the heat conduction mechanism. We then elaborate on these methods for improving the overall thermal conductivity of the composites made of h-BNNS and polymers with a special focus on modification, hybrid filling and alignment in the matrix. Finally, we provide a brief introduction on the applications of the composite materials and prospect the future challenges of insulating and thermally conductive materials.