Flexible and Ultrathin Graphene/Aramid Nanofiber Carbonizing Films with Nacre-like Structures for Heat-Conducting Electromagnetic Wave Shielding/Absorption

Abstract

Electromagnetic interference (EMI) shielding and electromagnetic wave absorption (EWA) materials with good thermal management and flexibility properties are urgently needed to meet the more complex modern service environment, especially in the field of smart wearable electronics. How to balance the relation of electromagnetic performance, thermal management, flexibility, and thickness in material design is a crucial challenge. Herein, graphene nanosheets/aramid nanofiber (C-GNS/ANF) carbonizing films with nacre-like structures were fabricated via the blade-coating/carbonization procedure. The ingenious configuration from highly ordered alignment GNS interactively connected by a carbonized ANF network can effectively improve the thermal/electrical conductivity of a C-GNS/ANF film. Specifically, the ultrathin C-GNS/ANF film with a thickness of 17 μm shows excellent in-plane thermal conductivity (TC) of 79.26 W m–1 K–1 and superior EMI shielding up to 56.30 dB. Moreover, the obtained C-GNS/ANF film can be used as a lightweight microwave absorber, achieving excellent microwave absorption performance with a minimum reflection loss of −56.07 dB at a thickness of 1.5 mm and a maximum effective absorption bandwidth of 5.28 GHz at an addition of only 5 wt %. Furthermore, the C-GNS/ANF films demonstrate good flexibility, outstanding thermal stability, and flame retardant properties. Overall, this work indicates a prospective direction for the development of the next generation of electromagnetic wave absorption/shielding materials with high-performance heat conduction.

Flexible Hierarchical Polyimide/Polypyrrole/Carbon Nanofiber Composite Films for Tunable Electromagnetic Interference Shielding

“…A plausible EMI shielding mechanism of PPy/CF films was demonstrated in Figure h. When the EMW is incident on the surface of the PPy/CF composite film, a part of the EMW is reflected by the PPy films due to the impedance mismatch between PPy and air . Subsequently, the transmitted EMW encounters PPy and dissipates in the form of heat energy due to multiple reflections .…”

“…When the EMW is incident on the surface of the PPy/CF composite film, a part of the EMW is reflected by the PPy films due to the impedance mismatch between PPy and air. 46 Subsequently, the transmitted EMW encounters PPy and dissipates in the form of heat energy due to multiple reflections. 47 Then, nearly 90% of the transmitted EMW is reflected due to the high reflection effect of CF, and the remaining EMW encounters the multilayer PPy films again for multiple reflection.…”

High-Performance Microwave Absorption Materials: Theory, Fabrication, and Functionalization

“…Graphene is a type of two-dimensional carbon material with a honeycomb structure . It has large specific surface area and high conductivity to produce conduction loss, which is conducive to the generation of resonance to absorb attenuate microwave. , Thus, it is a good choice for the synthesis of efficient MAMs. However, at the same time, the performance of MAMs containing only graphene are often limited by their poor dispersion and a single loss mechanism .…”

Structural effects of AgNWs/MXene in artificial nacre‐Like hybrid cellulose nanofiber films on electromagnetic interference (EMI) shielding performance

“…In general, the higher intrinsic electrical conductivity plays a crucial role in reflection and loss of EM waves. [21][22][23][24] Especially for the films, adding enough and effective conductive nanomaterials to form a good conductive path is the popular method. Various conductive nanomaterials like conductive polymers, carbonbased materials, and metal nanomaterials have been widely adopted to make EMI shielding films.…”