Facial fabrication of aramid composite insulating paper with high strength and good thermal conductivity

High strength and good thermal dissipation become the inevitable requirements for the next generation of insulation materials. Here, we report a facile method to prepare composite insulating papers by incorporating two-dimensional layered boron nitride nanosheets (BNNSs) into aramid nanofibers and aramid pulp. Their layer by-layer structure fabricated by a vacuum-assisted filtration of their mixture suspension is similar to "brick - mortar" arrangement, contributing to the enhanced mechanical properties due to their strong interaction. Meanwhile, BNNSs act as heat-conducting "bridges", which provide the phonon conduction channels and reduce the interface thermal contact resistance. The thermal conductivity of the composite paper with 20% loading of BNNS reaches 4.34 W m(-1) K-1 and the dielectric strength is up to 59.6 kV mm(-1); whereas, the values of the parallel sample without BNNS are only 0.98 W m(-1) K-1 and 25.1 kV mm(-1), respectively. The composite papers possess highly thermal conductivities, outstanding electrical insulation and thermal stabilities, and excellent mechanical strength and flexibility, showing great potential applications in the field of flexible electronics.