Heat-Shielding Nanobrick Wall for Carbon Fiber-Reinforced Polymer Composites

Owing to their excellent mechanical properties, carbon fiber-reinforced polymer (CFRP) composites have a broad spectrum of applications in aerospace, civil engineering, automotive, and numerous industrial fields. Despite their many advantages, the inherent lack of thermal stability of the polymer matrix results in the loss of the composite’s mechanical properties when exposed to elevated temperatures. In an effort to provide thermal protection, a multilayer film composed of tris(hydroxymethyl)-aminomethane (THAM)-buffered polyethylenimine (PEI) and vermiculite (VMT) clay was deposited on CFRP composites via layer-by-layer assembly. When subjected to the flame from a butane torch and mechanical loading, the polymer–clay nanobrick wall provides substantial thermal insulation, decreasing the temperature on the backside of the CFRP composites by as much as 100 °C. The PEI-THAM/VMT coating also helps to maintain the storage modulus of the composite and offers significant protection from oxidative degradation, as confirmed by dynamic mechanical analysis and X-ray photoelectron spectroscopy. The performance of this polymer–clay multilayer film provides excellent thermal barrier that can be used to protect advanced composite materials from extreme heat

One-Step Synthesis of Antioxidative Graphene-Wrapped Copper Nanoparticles on Flexible Substrates for Electronic and Electrocatalytic Applications

In this study, we report a novel, one-step synthesis method to fabricate multilayer graphene (MLG)-wrapped copper nanoparticles (CuNPs) directly on various substrates (e.g., polyimide film (PI), carbon cloth (CC), or Si wafer (Si)). The electrical resistivities of the pristine MLG-CuNPs/PI and MLG-CuNPs/Si were measured 1.7 × 10^–6 and 1.4 × 10^–6 Ω·m, respectively, of which both values are ∼100-fold lower than earlier reports. The MLG shell could remarkably prevent the Cu nanocore from serious damages after MLG-CuNPs being exposed to various harsh conditions. Both MLG-CuNPs/PI and MLG-CuNPs/Si retained almost their conductivities after ambient annealing at 150 °C. Furthermore, the flexible MLG-CuNPs/PI exhibits excellent mechanical durability after 1000 bending cycles. We also demonstrate that the MLG-CuNPs/PI can be used as promising source-drain electrodes in fabricating flexible graphene-based field-effect transistor (G-FET) devices. Finally, the MLG-CuNPs/CC was shown to possess high performance and durability toward hydrogen evolution reaction (HER)

Nanobrick Wall Multilayer Thin Films with High Dielectric Breakdown Strength

Current thermally conductive and electrically insulating insulation systems are struggling to meet the needs of modern electronics due to increasing heat generation and power densities. Little research has focused on creating insulation systems that excel at both dissipating heat and withstanding high voltages (i.e., have both high thermal conductivity and a high breakdown strength). Herein, a polyelectrolyte-based multilayer nanocomposite is demonstrated to be a thermally conductive high-voltage insulation. Through inclusion of both boehmite and vermiculite clay, the breakdown strength of the nanocomposite was increased by ≈115%. It was also found that this unique nanocomposite has an increase in its breakdown strength, modulus, and hydrophobicity when exposed to elevated temperatures. This readily scalable insulation exhibits a remarkable combination of breakdown strength (250 kV/mm) and thermal conductivity (0.16 W m–1 K–1) for a polyelectrolyte-based nanocomposite. This dual clay insulation is a step toward meeting the needs of the next generation of high-performance insulation systems

Nanobrick Wall Multilayer Thin Films with High Dielectric Breakdown Strength

Current thermally conductive and electrically insulating insulation systems are struggling to meet the needs of modern electronics due to increasing heat generation and power densities. Little research has focused on creating insulation systems that excel at both dissipating heat and withstanding high voltages (i.e., have both high thermal conductivity and a high breakdown strength). Herein, a polyelectrolyte-based multilayer nanocomposite is demonstrated to be a thermally conductive high-voltage insulation. Through inclusion of both boehmite and vermiculite clay, the breakdown strength of the nanocomposite was increased by ≈115%. It was also found that this unique nanocomposite has an increase in its breakdown strength, modulus, and hydrophobicity when exposed to elevated temperatures. This readily scalable insulation exhibits a remarkable combination of breakdown strength (250 kV/mm) and thermal conductivity (0.16 W m–1 K–1) for a polyelectrolyte-based nanocomposite. This dual clay insulation is a step toward meeting the needs of the next generation of high-performance insulation systems