An electrospinning–electrospraying technique for connecting electrospun fibers to enhance the thermal conductivity of boron nitride/polymer composite films

Electrospinning is sometimes used to prepare filler/polymer composite materials for thermal management owing to the linear filler orientation and convenient processing. However, the filler–polymer thermal resistance inside the electrospun fibers and the lack of effective connection between the electrospun fibers affect the filler utilization efficiency of electrospun films. In the present work, an electrospinning–electrospraying technique was applied as a new strategy to prepare filler–polymer composites, where electrospinning was used to provide the main heat conduction path, and electrospraying was adopted to connect the electrospun fibers and construct an extra heat conduction path. Finally, an electrospun–electrosprayed composite film with a thermal conductivity of 24.98 W/(m·K) at 40 wt% boron nitride nanosheet (BNNS) content was produced. The thermal conductivity of the electrospun–electrosprayed film with 30 wt% BNNS was 1.7 times that of the electrospun film. This study represents the first use of the electrospinning–electrospraying method to prepare high-thermal-conductivity composite materials, and this method shows great potential for the preparation of such materials for thermal management.