Three-dimensional boron nitride reinforced thermal conductive composites with high elasticity

Polymer-based thermally conductive composites have good interfacial contact, processability and stability. However, because of the low thermal conductivity of polymer materials, usually, a larger percentage of filler is required to achieve high thermal conductivity, which leads to a drop in the resilience of the composite. To solve this problem, a melamine-formaldehyde resin sponge (MS) was used as a skeleton to wrap boron nitride nanosheets (BNNS) through repeated layering assembly, successfully preparing a three-dimensional (3D) boron nitride network (BNNS@MS). The mixture of poly(vinylidene fluoride) and BNNS (PVDF/BNNS) was formed in the pores of the 3D network of BNNS@MS. Due to the existence of the continuous phonon conduction network, the BNNS@MS/PVDF exhibits good thermal conductivity and high elastic deformation (rebound at 90% compression). When the content of BNNS is about 5 wt%, the thermal conductivity of the BNNS@MS/PVDF is increased to 1.43 ± 0.2 W/mK, 51.1% higher than that of PVDF/BNNS. The solid heat conduction network and polymer interplay to achieve good thermal management ability, and the composites have an important application prospect in the field of wearable flexible electronic thermal management.