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[Display omitted] Polymer-based dielectrics with high thermal conductivity and superb dielectric properties hold great promising for advanced electronic packaging and thermal management application. However, integrating these properties into a single material remains challenging due to their mutually exclusive physical connotations. Here, an ideal dielectric thermally conductive epoxy composite is successfully prepared by incorporating multiscale hybrid fillers of boron nitride microsphere (BNMS) and silicon dioxide coated silicon carbide nanoparticles (SiC@SiO 2). In the resultant composites, the microscale BNMS serve as the principal building blocks to establish the thermally conductive network, while the nanoscale SiC@SiO 2 as bridges to optimize the heat transfer and suppress the interfacial phonon scattering. In addition, the special core–shell nanoarchitecture of SiC@SiO 2 can significantly impede the leakage current and generate a great deal of minicapacitors in the composites. Consequently, favorable thermal conductivity (0.76 W/mK) and dielectric constant (∼8.19) are simultaneously achieved in the BNMS/SiC@SiO 2 /Epoxy composites without compromising the dielectric loss (∼0.022). The strategy described in this study provides important insights into the design of high-performance dielectric composites by capitalizing on the merits of different particles. [ABSTRACT FROM AUTHOR]

Dielectric materials with excellent thermal stability, mechanical properties, and thermal conductivity are highly desirable for advanced electronics and electrical equipment. However, it remains a significant challenge to develop a single material with these properties. Here we describe a new strategy to prepare dielectric paper by combining one-dimensional aramid nanofiber (ANF) with two-dimensional fluorinated graphene (F-graphene) through a vacuum-assisted filtration method. The obtained ANF/F-graphene paper exhibits a low dielectric constant of 1.92 at 103 Hz and its electrical breakdown strength is 17.6% higher than that of the neat ANF paper, owing to the presence of F-graphene, which significantly suppresses the accumulation of space charge in the prepared paper. Moreover, high mechanical strength (>200 MPa), thermal conductivity (6.29 Wm−1K−1), and thermal decomposition temperature (>500°C) are simultaneously achieved for the ANF/F-graphene paper. These findings highlight the fabrication of multifunctional dielectric materials and broaden their practical applications in the field of high-temperature electronics and devices. [ABSTRACT FROM AUTHOR]

The developments in the high-power densities and high integration of electronic devices have put forward higher requirements for advanced thermal management materials (TMMs) to meet the rising demand for heat dissipation. However, it has remained a major challenge to achieve significant enhancement of thermal conductivity (TC) of TMMs without compromising their mechanical and dielectric properties. Here, we report a flexible, thermally conductive composite film that contain aramid nanofiber (ANF) and silver nanoparticles (AgNPs) decorated with boron nitride (BN), the in-plane TC of which is up to 12 W/mK at 40 wt.% filler contents. Such a high TC is attributed to the bridging role of AgNPs, which greatly reduces the interfacial thermal resistance of composites. At the same time, the as-prepared composite films possess outstanding mechanical strength (>126 MPa), owing to the coupling between the ANF network and the favourable hydrogen bonding interaction between the ANF and the functional BN. Moreover, a low dielectric loss (<0.05), high electrical resistivity (~1014 Ω·cm), and high decomposition temperature (>500°C) are simultaneously achieved for the composite films. These findings offer a facile strategy for the design of multifunctional TMMs, which hold great promising for application in electric devices. [ABSTRACT FROM AUTHOR]

[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]

Dielectric materials with superb thermal and electrical properties are highly desired for high-voltage electrical equipment and advanced electronics. Here, we propose a novel strategy to improve the performance of epoxy composites by employing boron nitride nanosheets (BNNSs) and γ-glycidyl ether oxypropyl sesimoxane (G-POSS) as functional fillers. The resultant ternary epoxy composites exhibit high electrical resistivity (1.63 × 1013 Ω·cm) and low dielectric loss (<0.01) due to the ultra-low dielectric constants of cage-structure of G-POSS. In addition, a high thermal conductivity of 0.3969 W·m−1·K−1 is achieved for the epoxy composites, which is 114.66% higher than that of pure epoxy resin. This can be attributed to the high aspect ratio and excellent thermally conductive characteristics of BNNSs, promoting phonon propagation in the composites. Moreover, the epoxy composite simultaneously possesses remarkable dynamic mechanical properties and thermal stability. It is believed that this work provides a universal strategy for designing and fabricating multifunctional composites using a combination of different functional fillers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hybrid particles are synthesized from boron nitride and barium titanate. • Composite films prepared by incorporating hybrid particles into cyanoethyl cellulose. • The composite exhibits a high dielectric constant of ∼ 44. • High thermal conductivity and breakdown strength are also achieved in the composite. Polymer dielectrics hold a great potential to be used in the field of power equipment and advanced electronics. However, their limited thermal conductivity fails to satisfy the imperative demand for heat dissipation in practical applications. Herein, we report a novel strategy to prepare multifunctional cyanoethyl cellulose matrix composite films by employing a hybrid filler of boron nitride nanosheets and barium titanate nanoparticles. The resultant composite films simultaneously exhibit high thermal conductivity (∼10.54 W/m·K), high dielectric constant (∼44), high electrical breakdown strength (>302 kV/mm), and low dielectric loss (∼0.01). The findings in this work enable broader application of polymer dielectrics in impulse power and energy storage devices. [ABSTRACT FROM AUTHOR]

Polymer-based dielectric films with desirable heat dissipation property hold great promise as thermal management materials in advanced electronics and high power devices. Herein, we report a new strategy for preparing thermally conductive films by synergistically combining one-dimensional (1D) aramid nanofiber (ANF) with 2D edge-hydroxylated boron nitride nanosheet (OH-BNNS) via a vacuum-assisted self-assembly technique. The obtained ANF/OH-BNNS film exhibits an ultrahigh in-plane thermal conductivity of 32.3 W m−1K−1 at 40 wt% BNNS-OH loading, which is 3530% greater than that of the pure ANF film. The excellent thermal conductivity results from the special 'brick-and-mortar' layered structure of ANF/OH-BNNS, in which the increased contacting and overlapping of OH-BNNS promotes the formation of the thermal conduction pathways. In addition, the rigid ANFs act as bridges linking OH-BNNS by favorable hydrogen bonding interactions, which efficiently enhance phonon propagation and stress transfer in the film. Moreover, the ANF/OH-BNNS film simultaneously shows low dielectric loss (~0.03), high tensile strength (~88 MPa), and a high decomposition temperature (>510 °C). We believe that these findings are of great importance for the fabrication and practical application of thermal management materials in high-temperature electronics and devices. [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]