Spray-assisted assembled spherical boron nitride as fillers for polymers with enhanced thermally conductivity

Owing to its unique properties, such as electrical insulation, high thermal conductivity, high breakdown strength, physical and chemical stability, boron nitride has been used widely as fillers to improve the thermal conductivity of polymers. However, the addition of very small boron nitride leads to a dramatic increase of viscosity of polymer composites. The increased viscosity will limit the amount of boron nitride in polymers, which results in limited increase of thermal conductivity for polymer composites. To this end, we developed a spray-assisted self-assembly method to prepare spherical boron nitride. The spherical boron nitride improves the thermal conductivity of polydimethylsiloxane, in contrast to boron nitride platelets, which is attributed to its structural characteristics. The thermal conductivity of spherical boron nitride/polydimethylsiloxane is up to 2.30 W/mK, almost four times of that of platelet-like BN/polydimethylsiloxane composite at the 50 wt% filler content. This simple and versatile method is therefore directly relevant to the future design of practical polymer composites for heat removal of modern electronics.