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[Display omitted] • A composite paper was prepared by combining aramid nanofibers, boron nitride nanotubes, and polyethyleneimine. • Elaborating interfacial hydrogen bonds design can optimize the mechanical properties of composite paper. • The composite paper has high thermal conductivity and unique dielectric performance. Aramid paper is ubiquitous in advanced electronics and high-voltage equipment by virtue of their outstanding dielectric properties, mechanical reliability, and thermal stability. However, their limited thermal conductivity still fails to satisfy the stringent demands for heat dissipation in applications with high power and high energy density. Herein, we report a highly thermally conductive composite paper prepared by synergistically combining one-dimensional (1D) aramid nanofibers (ANFs), 1D edge-hydroxylated boron nitride nanotubes (BNNTs), and polyethyleneimine (PEI). The resultant composite paper exhibits high thermal conductivity (9.91 Wm−1K−1), low dielectric loss (<0.01), and ultrahigh electrical breakdown strength (∼334 kV/mm) with an exceptional heat resistance performance. Three-dimensional hydrogen bonding networks were constructed between the ANF framework, PEI, and BNNTs, endowing the composite paper with a superior tensile strength (up to 317 MPa) and Young's modulus (∼7.7 GPa), which are significantly higher than those of the commercial Nomex T410 paper. This research provides important insights into the design and fabrication of multifunctional insulating paper for application in modern integrated electronic and power systems. [ABSTRACT FROM AUTHOR]

Polymer composites with high thermal conductivity have promising applications for the thermal management of modern electronic devices. Here, a novel strategy is proposed to enhance the thermal conductivity of epoxy composites by employing a hybrid graphene and boron nitride nanoparticle (GBN). In the GBN, boron nitride nanosheets (BNNSs) tightly adsorb onto the surface of graphene via π-π interactions, and act as bridges for conveying phonons as well as barriers for electrons transporting between adjacent graphene particles. The thermal conductivity and dielectric properties of composites containing GBN are then systematically investigated. The thermal conductivity is significantly enhanced (~140%) in GBN/epoxy composites containing only 5 wt% of GBN. High electrical resistivity (3.05 × 1012 Ω·cm) and low dielectric loss (tan δ < 0.08) are also observed. This study provides important insights into the design and fabrication of highly thermally conductive and electrically insulating composites. Unlabelled Image • Hybrid nanoparticles consisting of graphene and boron nitride nanosheets are prepared by combination of sonication and hydrothermal treatment. • Boron nitride nanosheets act as bridges for phonons conveying as well as barriers for electrons transporting between adjacent graphene particles. • Significant thermal conductivity enhancement is achieved at a low hybrid filler loading. [ABSTRACT FROM AUTHOR]