The development of low loading fraction nanoscale reinforcements that can be used to improve the dielectric and thermal properties of a polymer remains a challenge by the reason of the insurmountable difficulties with exfoliation and dispersion of polymer nanocomposites. Here, we combined noodle‐like boron nitride nanoribbons (BNNRs) with epoxy resin (EP) by a facile in situ synthesis. The hydroxyl and amino on the BNNRs surface can not only improve dispersibility but also conduct the formation of EP with BNNRs by the in situ ring‐opening reaction. The thermal behavior, dielectric properties, and thermal conductivity of BNNRs/EP nanocomposites with different BNNRs contents were investigated. At an extremely low BNNRs loading fraction of 1 wt%, the thermal conductivity of the nanocomposite increased 48%, which is attributed to the long continuous heat conduction path formed by the strong integration of BNNRs and EP. In addition, the electrical breakdown strength increased from 95.58 to 159.17 kV·mm−1 as the BNNRs content increased, while the nanocomposites maintained acceptable dielectric properties. The results indicate the potential for BNNRs as a new class of nanofiller for dielectric polymers.

Thermoelectric materials are attractive for the reversible conversion between thermal and electrical energy. The preparation of bulk thermoelectric materials usually involves multi-step processes with considerable time and energy consumption, which...

The enhancement of the heat-dissipation property of polymerbased composites is of great practical interest in modern electronics. Recently, the construction of a three-dimensional (3D) thermal pathway network structure for composites has become an attractive way. However, for most reported high thermal conductive composites, excellent properties are achieved at a high filler loading and the building of a 3D network structure usually requires complex steps, which greatly restrict the large-scale preparation and application of high thermal conductive polymer-based materials. Herein, utilizing the framework-forming characteristic of polymerization-induced para-aramid nanofibers (PANF) and the high thermal conductivity of hexagonal boron nitride nanosheets (BNNS), a 3D-laminated PANF-supported BNNS aerogel was successfully prepared via a simple vacuum-assisted self-stacking method, which could be used as a thermal conductive skeleton for epoxy resin (EP). The obtained PANF-BNNS/EP nanocomposite exhibits a high thermal conductivity of 3.66 W m −1 K −1 at only 13.2 vol % BNNS loading. The effectiveness of the heat conduction path was proved by finite element analysis. The PANF-BNNS/EP nanocomposite shows outstanding practical thermal management capability, excellent thermal stability, low dielectric constant, and dielectric loss, making it a reliable material for electronic packaging applications. This work also offers a potential and promotable strategy for the easy manufacture of 3D anisotropic high-efficiency thermal conductive network structures.