With the emergence of the 5G era, the high-precision operation of electronic devices usually results in high heat flux and increases the local heating power, seriously limiting their stability and service life. This paper presents a method for producing a thermally conductive filler by first noncovalently modifying silicon carbide (SiC) particle with poly(catechol/polyamine) (PCPA) and then covalently functionalizing it with 3-mercapto-propylethoxy-bis(tridecyl-pentaethoxy-siloxane) (Si747), which is labeled as SiC-PCPA-Si747. Next, the prepared SiC-PCPA-Si747 filler is added to the natural rubber (NR) matrix for producing SiC-PCPA-Si747/NR composites with high thermal conductivity (λ). The noncovalent modification of PCPA preserves the intrinsic λ of SiC, while the covalent functionalization with Si747 enhances the interfacial interaction between the filler and NR matrix. As a result of the reduced interfacial thermal resistance and the formation of high-efficiency heat conduction channels, the NR composite filled with 50 vol % SiC-PCPA-Si747 filler shows a λ value of 0.4980 W/(m·K), which is about 475% higher than that of pure NR (0.0866 W/(m·K)). In short, this method is cost-effective and feasible and can be used to fabricate polymeric composites with high λ that can meet the future demands of advanced electronic devices.
Graphite films are widely used in microelectronic devices as heat-dissipation materials due to their high thermal conductivity, low thermal expansion coefficient and lightweight. In the 5G era, the miniaturization and integration of microelectronic devices are continuously improving, so there are higher requirements for heat-dissipation materials. Therefore, flexible graphite films with high thermal conductivity are urgently needed. In this work, nickel-coated CNTs (Ni@CNTs) were prepared first as additives to be incorporated into the PI matrix via in situ polymerization, and then the Ni@CNTs/PI composite films were carbonized and graphitized at high temperature to form graphite films. In this composite system, nickel particles can effectively improve the graphitization degree of the obtained graphite films, which is beneficial to the improvement of their thermal conductivity, as well as the CNTs can effectively enhance the cross-plane thermal conductivity and mechanical strength of the graphite films. The graphite films obtained from the graphitization of PI/Ni@CNTs (0.4 wt%) have a perfect graphene structure and optimal properties. The optimal layer thickness of graphene is 0.3354 nm, while the d-spacing of the graphite layers is around 0.3358 nm. The in-plane thermal conductivity is 1.13 times greater than that of the graphite film made from the pure PI film (G0 film), which has a value of 1198.5 W m−1 K−1. The cross-plane thermal conductivity is 6.26 W m−1 K−1, which is 2.96 times that of the G0 film (2.11 W m−1 K−1). The bending strength is 72.3 Mpa, which is 2.28 times that of the G0 film (31.7 Mpa). The introduction of Ni@CNTs greatly improves the comprehensive properties of graphite films, and the preparation technology has an important guiding significance for the preparation of high thermal conductivity flexible graphite films and important industrial application value.
With the increasing popularity of modern electronic devices in the fifth-generation (5G) era, high-performance and high-safety electrically insulating materials with good mechanical flexibility and strength, high thermal stability and fire resistance are urgently needed. Herein, we report a highly flexible, thermally stable, and fire-retardant nanocomposite paper with high dielectric breakdown strength and mechanical strength by synergistically integrating one-dimensional ultralong hydroxyapatite (HAP) nanowires and aramid nanofibers (ANFs) through the vacuum-assisted filtration process. The as-prepared HAP/ANF nanocomposite paper has a nanowire/nanofiber networked framework and a layered structure, and exhibits high tensile strength (73.5 MPa), fracture strain (7.4 %), folding durability (1396 times under a loading weight of 9.8 N), excellent flexibility, and good processibility. Notably, the HAP/ANF nanocomposite paper has a superior dielectric breakdown strength (92.4 kV mm −1 ), high thermal stability and flame retardancy in comparison with the commercial Nomex T410 electrical insulation paper. The multifunctional HAP/ANF nanocomposite paper is promising for applications in miniaturized and flexible electronic devices, high-voltage electrical insulation equipments, and fire-retardant and high-temperature fields.
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