Abstract
High-performance electromagnetic interference shielding is becoming vital for the next generation of telecommunication and sensor devices among which portable and wearable applications require highly flexible and lightweight materials having efficient absorption-dominant shielding. Herein, we report on lightweight carbon foam–carbon nanotube/carbon nanofiber nanocomposites that are synthesized in a two-step robust process including a simple carbonization of open-pore structure melamine foams and subsequent growth of carbon nanotubes/nanofibers by chemical vapor deposition. The microstructure of the nanocomposites resembles a 3-dimensional hierarchical network of carbonaceous skeleton surrounded with a tangled web of bamboo-shaped carbon nanotubes and layered graphitic carbon nanofibers. The microstructure of the porous composite enables absorption-dominant (absorbance ∼0.9) electromagnetic interference shielding with an effectiveness of ∼20–30 dB and with an equivalent mass density normalized shielding effectiveness of ∼800–1700 dB cm3 g–1 at the K-band frequency (18–26.5 GHz). Moreover, the hydrophobic nature of the materials grants water-repellency and stability in humid conditions important for reliable operation in outdoor use, whereas the mechanical flexibility and durability with excellent piezoresistive behavior enable strain-responsive tuning of electrical conductivity and electromagnetic interference shielding, adding on further functionalities. The demonstrated nanocomposites are versatile and will contribute to the development of reliable devices not only in telecommunication but also in wearable electronics, aerospace engineering, and robotics among others.
Highlights
High-performance electromagnetic interference (EMI) shielding based on advanced functional materials are of high demand for the next-generation portable and wearable devices, as they play a key role in reducing the adverse effects of electromagnetic radiation on electrical components enabling future reliable technologies related to the internet-of-things and digitalization
Carbon nanotubes and nanofibers were synthesized by water assisted chemical vapor deposition (WA-CVD) at 770 °C in the same tube furnace by switching the gas flow for acetylene as carbon source filling the carbon foam skeletal structure with carbon nanotubes (CNTs) and CNFs (Figures S1 and S2, Supporting Information)
The hierarchical carbon nanocomposites retained the excellent flexibility of the original carbon foam. (Figure 2b; Movie S1, Supporting Information)
Summary
High-performance electromagnetic interference (EMI) shielding based on advanced functional materials are of high demand for the next-generation portable and wearable devices, as they play a key role in reducing the adverse effects of electromagnetic radiation on electrical components enabling future reliable technologies related to the internet-of-things and digitalization. These materials are anticipated to be lightweight and flexible yet durable and stable in harsh environments. In multiphase materials, additional scattering of the waves occurs at the interfaces of different phases The degree of such interfacial scattering is a function of the impedance mismatch between the corresponding media that depends on the dielectric permittivity and magnetic permeability of the phases. In such systems shielding is a consequence of multiple scattering events in the medium, which inherently increase the path of propagation and the attenuation of electromagnetic waves
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call