"Three-in-One" Multi-Scale Structural Design of Carbon Fiber-Based Composites for Personal Electromagnetic Protection and Thermal Management

Abstract

Wearable devices with efficient thermal management and electromagnetic interference (EMI) shielding are highly desirable for improving human comfort and safety. Herein, a multifunctional wearable carbon fibers (CF) @ polyaniline (PANI) / silver nanowires (Ag NWs) composites with a “branch-trunk” interlocked micro/nanostructure were achieved through "three-in-one" multi-scale design. The reasonable assembly of the three kinds of one-dimensional (1D) materials can fully exert their excellent properties i.e., the superior flexibility of CF, the robustness of PANI, and the splendid conductivity of AgNWs. Consequently, the constructed flexible composite demonstrates enhanced mechanical properties with a tensile stress of 1.2 MPa, which was almost 6 times that of the original material. This is mainly attributed to the fact that the PNAI (branch) was firmly attached to the CF (trunk) through polydopamine (PDA), forming a robust interlocked structure. Meanwhile, the composite possesses excellent thermal insulation and heat preservation capacity owing to the synergistically low thermal conductivity and emissivity. More importantly, the conductive path of the composite established by the three 1D materials greatly improved its EMI shielding property and Joule heating performance at low applied voltage. This work paves the way for rational utilization of the intrinsic properties of 1D materials, as well as provides a promising strategy for designing wearable electromagnetic protection and thermal energy management devices.

Porous Carbon/ZnO Composites Synthesized Using an Environmentally Friendly Metal–Polyphenol Network for Electromagnetic Wave Absorption

“…According to eq , the dielectric loss mechanism mainly encompasses polarization loss ( ε p ) and resistance loss ( ε σ ). The resistance loss is proportional to the conductivity, which in turn is related to the graphitization degree of the MPN-derived PC layer. , From the Raman spectra results, it can be seen that the graphitization degree and resistance loss increase significantly as the pyrolysis temperature increases from 600 to 700 °C/800 °C. The PC in the PC/ZnO-700 and -800 composites can act as a conductive network in the paraffin matrix and promote electron movement, which would result in the generation of microcurrents and consequent electromagnetic wave energy dissipation. , According to the Debye relaxation theory, when the resistance loss is negligible, ε′ and ε″ obey the following equation: true( ε ′ − ε s + ε ∞ 2 true) 2 + ε ″ 2 = true( ε s − ε ∞ 2 true) 2 If the ε′−ε″ curve has the form of a semicircle, it can be concluded that the tested material dissipates energy via a polarization relaxation process, and each semicircle corresponds to an individual Debye relaxation process .…”

“…The resistance loss is proportional to the conductivity, which in turn is related to the graphitization degree of the MPN-derived PC layer. 54,55 From the Raman spectra results, it can be seen that the graphitization degree and resistance loss increase significantly as the pyrolysis temperature increases from 600 to 700 °C/800 °C. The PC in the PC/ZnO-700 and -800 composites can act as a conductive network in the paraffin matrix and promote electron movement, which would result in the generation of microcurrents and consequent electromagnetic wave energy dissipation.…”

Construction of a hollow nickel–magnesium ferrite decorated nitrogen-doped reduced graphene oxide composite aerogel for highly efficient and broadband microwave absorption

“…Therefore, the unique porous structure in the NRGO/hollow Ni 0.5 Mg 0.5 Fe 2 O 4 composite aerogel will improve the impedance matching between the absorber and air through regulating the complex permittivity. 24,40,43,44 In addition, when the incident waves penetrate into the 3D porous network structure of the NRGO/hollow Ni 0.5 Mg 0.5 Fe 2 O 4 composite aerogel, multiple reflection will occur at the walls of the holes to attenuate the electromagnetic energy. 19,24,40 Secondly, the structural defects and residual oxygen-containing functional groups on the surfaces of NRGO could act as the polarization centers, resulting in the imbalance of the dipole moment and the formation of dipole polarization under the alternating electromagnetic field, which further improves the microwave attenuation capacity.…”

Achieving Superior Electromagnetic-Absorbing Performances in the Hexagonal Flake BaFe12O19@PVDF Composites

“…Moreover, as the PVDF content in the composites increases, ε′ gradually decreases, while ε″ initially increases and subsequently decreases. On the one hand, PVDF is a dielectric material, and its dielectric constant is lower than that of hexagonal flake BaFe 12 O 19 , so an increase in its content will inevitably lead to a decrease in the dielectric constant of the composites. , …”

“…On the one hand, PVDF is a dielectric material, and its dielectric constant is lower than that of hexagonal flake BaFe 12 O 19 , so an increase in its content will inevitably lead to a decrease in the dielectric constant of the composites. 32,33 At the same time, PVDF is also an insulating material and does not contribute significantly to conductive losses. Instead, it primarily contributes to polarization losses, including electron polarization, ion polarization, and dipole polarization.…”