Wanchun Jiang

A self-assembly method for the fabrication of a three-dimensional (3D) polypyrrole (PPy)/poly(3,4-ethylenedioxythiophene) (PEDOT) hybrid composite with excellent absorption performance against electromagnetic pollution

Electromagnetic pollution is second to air and water pollution, and has been considered as the third worldwide hazard. Materials with electromagnetic absorption (EA) performance are the key to protect human beings and wildlife from this pollution. In this study, a composite comprising three-dimensional (3D) polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) was prepared via a self-assembly method. This 3D-PPy/PEDOT composite was characterized using field emission scanning electron microscopy (FE-SEM), field emission high resolution transmission electron microscopy (FE-HRTEM), X-ray diffraction (XRD) and Raman spectroscopy. It was found that a composite only consisting of 5 wt% 3D-PPy/PEDOT in a wax matrix exhibited an effective EA bandwidth (deeper than −10 dB) of 6.24 GHz at a thickness of 2.5 mm. Furthermore, the highest effective EA bandwidth of 6.28 GHz can be reached. The results obtained in this study indicate that 3D-PPy/PEDOT is a promising EA material, which can exhibit a broad effective EA bandwidth at a low filler loading and a thin thickness simultaneously.

A core–shell polypyrrole@silicon carbide nanowire (PPy@SiC) nanocomposite for the broadband elimination of electromagnetic pollution

Design and fabrication of electromagnetic absorption (EA) materials are important nowadays, due to deepening electromagnetic pollution. In this study, a convenient process has been developed for the in situ self-assembly preparation of core–shell PPy@SiC nanocomposites, which have been used for the elimination of electromagnetic pollution. It was found that a composite consisting of only 10 wt% PPy@SiC nanocomposite exhibited an effective EA bandwidth (deeper than −10 dB) of 6.52 GHz at a thickness of 2.5 mm. These findings open up a new facile way for multi-band electromagnetic attenuation.

Growing 3D ZnO nano-crystals on 1D SiC nanowires: enhancement of dielectric properties and excellent electromagnetic absorption performance

Nowadays, only by balancing the relationship of electromagnetic applications and electromagnetic pollution management can human health and quality of life be guaranteed. SiC nanowires have long-term thermodynamic stability and they are widely used in special applications. However, their poor dielectric properties hindered the improvement of electromagnetic absorption (EA) performance. Light weight and high efficiency are two key factors for EA materials. In this study ZnO nano-crystals were grown on SiC nanowires through an easy scale-up double hydrolysis reaction method. With significant increments in complex permittivity, a composite loaded with 30 wt% of as-prepared sample can achieve an effective EA bandwidth (≤−10 dB) of 6.60 GHz at the thickness of 2.5 mm (11.08–17.68 GHz). The outstanding properties of the as-prepared sample imply that it is a promising nano-material in the world of EA.

Interfacial synthesis of polypyrrole microparticles for effective dissipation of electromagnetic waves

A strategy has been adopted to regulate the dielectric properties of polypyrrole microparticles for good electromagnetic absorption performance through an interfacial synthesis process. Classical Debye relaxation theory and resistor-capacitor model have been employed to illustrate the electromagnetic dissipation mechanism of polypyrrole microparticles. The prepared polypyrrole microparticles exhibit an effective electromagnetic absorption bandwidth 5.48 GHz (deeper than −10 dB) from 12.52 to 18 GHz with a filler loading of 15 wt. % in paraffin. It was demonstrated that the morphologies of conducting polymers can significantly affect the dissipation of electromagnetic waves, supplying a strategy for the design of effective electromagnetic absorption materials.

Chiral induced synthesis of helical polypyrrole (PPy) nano-structures: a lightweight and high-performance material against electromagnetic pollution

Helical conducting polymer nano-structures have attracted increasing attention because of their superior optical and electrical activities, lightweight, and flexibility as well as controllable morphologies at several levels of a hierarchy. Nevertheless, hardly any research has focused on helical conducting polymer nano-structure based electromagnetic protecting materials. Herein, we synthesized single-handed helical polypyrrole (PPy) nano-structures by a chiral inducing route and demonstrated their amazing electromagnetic protecting abilities. A gradually constructed conducting network and helical chirality may be the main reasons for the tunable and impressive electromagnetic protecting performance of the as-prepared helical PPy nano-structures. This research opens up an opportunity for the application of single-handed helical conducting polymer nano-structures as a lightweight and tunable high-performance electromagnetic protecting material, especially in the fields of special aircraft, aerospace and fast-growing next-generation flexible electronics.

Three-dimensional (3D) α-Fe2O3/polypyrrole (PPy) nanocomposite for effective electromagnetic absorption

The lightweight and 3-dimensional reticulated α-Fe2O3/PPy hybrids were successfully fabricated via a facile one-pot polyreaction. The measured complex permittivity and microwave attenuation performance suggest that the dielectric properties of PPy can be regulated by the mass ratio of added α-Fe2O3. The two dielectric resonance peaks of complex permittivity can be ascribed to the interface capacitor-like structure. An equivalent circuit model was established to explain the nonlinear resonance behavior of the α-Fe2O3/PPy wax composites. The addition of α-Fe2O3 properly tuned the dielectric constant to endow the composites with highly efficient microwave absorption. The minimum reflection loss of α-Fe2O3/PPy wax composites were enhanced to nearly −29dB with an effective bandwidth (RL≤ − 10dB) up to 5.0GHz. The numerical method was proposed to calculate the optimum thickness for minimum RL at expected frequency by detailed investigation on the transmission formula. Moreover, the required thickness for optimum absorption efficiency at expected frequency can be obtained directly.

Using γ-Fe2O3 to tune the electromagnetic properties of three-dimensional (3D) polypyrrole (PPy) and its broadband electromagnetic absorber

Electromagnetism such as gravity can be considered an omnipresent force, which plays an important role in the functional activities of organisms. However, electromagnetic waves with different frequencies have aroused various harmful factors in human beings and wildlife. With the tunable dielectric property, the material can get a controllable electromagnetic absorption range against different types of electromagnetic pollution. In this study, we reported that nano γ-Fe2O3 can regularly tune the dielectric properties of the three dimensional (3D) polypyrrole (PPy) aerogel. On the one hand, it has advantages such as a rapid synthesis strategy (only several minutes), facile purification process (with only water), and on the other hand, this aerogel based absorber can reach effective EA bandwidths of 6.76 GHz (≤−10 dB, 90% electromagnetic energy was attenuated) and 1.88 GHz (≤−20 dB, 99% electromagnetic energy was attenuated) simultaneously at a thickness of 2.5 mm.

Microwave absorption of a TiO2@PPy hybrid and its nonlinear dielectric resonant attenuation mechanism

We report on a high-performance electromagnetic absorption material (TiO2@PPy) developed via a facile in situ polymerization process, where lower than −60 dB maximum absorption and 6.56 dB effective absorption bandwidth (lower than −10 dB) can be obtained under low thickness. The excellent electromagnetic wave absorption ability is attributed to the synthetic effect of improved impedance matching and the dual loss mechanism, which originates from the polarization relaxations of dipoles induced by vacancy defects and a conductive network constructed by aerogels. An equivalent circuit model is established to explicate the nonlinear dielectric resonant attenuation mechanism.

Carboxyl multiwalled carbon nanotubes modified polypyrrole (PPy) aerogel for enhanced electromagnetic absorption

Polypyrrole (PPy) aerogel is a low-cost and lightweight material with high-performance electromagnetic absorption (EA). However, it does not always meet the requirements of practical applications. In this study, we used trace amounts of carboxyl multiwalled carbon nanotubes to regulate the dielectric property of PPy aerogel, thus enhancing the EA performance. Furthermore, the reason for enhanced EA performance can be elaborated by an electron blocking mechanism.

The hybrid of SnO2 nanoparticle and polypyrrole aerogel: an excellent electromagnetic wave absorbing materials

As a kind of costless and lightweight material, SnO2 nanoparticles@polypyrrole hybrid aerogels have been synthesized and displayed electromagnetic wave absorbing (EWA) performance. Only with 10 wt% of nano-SnO2 filler loading in wax, effective EWA bandwidth of the hybrid aerogel can reach 7.28 GHz which is the widest lightweight EWA material among the reported absorbents. Through the regulation of sample thicknesses, effective EWA at lower frequencies can also be achieved. It was demonstrated that this aerogel can be used as an effective lightweight broadband EWA material.