Heterointerface Effects in Electrospun Carbon Nanotube/Poly(vinylidene difluoride) Nanofibrous Mats for Microwave Absorption

Abstract

Developing highly flexible, mechanically strong, and highly efficient microwave absorption materials is urgently needed to solve the electromagnetic (EM) wave pollution problems in the areas of fast-growing electronic devices. Herein, poly(vinylidene difluoride) (PVDF) composite nanofibrous mats combined with functionalized carbon nanotubes (CNTs) were fabricated by a facile electrospinning process. The hydrogen-bonding heterointerfaces between PVDF and acidified CNTs (a-CNTs) favored interfacial polarization relaxation compared with the covalent heterointerfaces between PVDF and aminated CNTs (NH 2 − CNTs), resulting in better microwave absorption performance. Furthermore, 4,4′-diaminodiphenylsulfone (DDS) was adopted as the chemical cross-linking agent. The PVDF nanocomposite nanofibrous mats with 0.25 wt % DDS exhibited excellent microwave absorbing properties with a minimum reflection loss (RL min ) of −30.4 dB at 7.2 GHz and a thickness of 3.4 mm as well as an effective absorption bandwidth of 5.0 GHz at a thickness of 1.6 mm. More importantly, the mechanical properties were improved simultaneously, because of the cross-linking reaction occurring within the PVDF nanofibers. A tensile strength and a modulus of 1.2 and 21.7 MPa were achieved, respectively. The provided strategy would facilitate the design of highly flexible and mechanically strong electrospun nanofibrous mats for microwave absorption applications.

Influence of Exfoliated Boron Nitride for Fabrication of a Lightweight Wideband Microwave Absorbing Material

“…If the magnetic loss results from the Eddy current loss, the values of C 0 ( C 0 μ″(μ′) −2 f –1 ) are unaffected by frequency fluctuations. , It is possible that the Eddy current loss is not the primary magnetic loss mechanism for the sample of 15-NiFBN-0.75 because of a significant fluctuation in 9.9 GHz (Figure b). However, the magnetic loss mechanism for 15-NiFBN-0.5 and 15-NiFBN-1 samples may be attributed to the Eddy current loss dominated since the C 0 values are almost unchanged throughout the range of 8.2–12.4 GHz.…”

“…The absorption property depends on materials’ conductivity, impedance matching, and microstructures. − For microwave absorption, many composite materials are developed, including dielectric materials for dielectric loss, magnetic materials for hysteresis and eddy current loss, and conducting materials for electrical loss and multiple reflections. Individually, however, they exhibit limited bandwidth absorption. , Researchers use a combination of dielectric, magnetic, and conducting materials to achieve wideband microwave absorption.…”

“…Individually, however, they exhibit limited bandwidth absorption. 14,15 Researchers use a combination of dielectric, magnetic, and conducting materials to achieve wideband microwave absorption.…”

Microstructure controllable polyimide/MXene composite aerogels for high-temperature thermal insulation and microwave absorption

“…The real part e 0 represents the storage ability, while the imaginary part e 00 denotes the dissipation ability of microwave energy. 35 In Fig. 6(a) and (b), the e 0 of the composite aerogels decreased with decreasing pore size.…”

Cross-linking electrospinning

“…A similar reaction also occurred in the cross-linking of acidified CNT/PVDF nanofibers by 4,4′-diaminodiphenylsulfone (DDS) (amide reaction between DDS and acidified CNTs with carboxyl groups and dehydrofluorination of PVDF generating CvN double bonds). 133 Additionally, ethanediamine (EDA) 134 was used to cross-link polyetherimide (PEI), while hexamethylene diamine (HDA) 135,136 was used to cross-link polyimide (PI). In the process, the amidation reaction between the imide groups (rings) on PEI/PI and amine groups of the cross-linking agents led to covalent cross-linking, as shown in Fig.…”