Facile synthesis of coral cauliflower‐like polypyrrole hemispheres toward screening electromagnetic interference pollution

Abstract

In this study, coral cauliflower‐like polypyrrole (PPy) hemispheres are synthesized on an alumina substrate via a simple chemical oxidative polymerization route. The stony coral‐like morphology of PPy hemispheres acts as a conducting trap in absorbing electromagnetic (EM) radiation via multiple internal reflections. A PPy thin film deposited at 0.2 M pyrrole concentration shows a minimum reflection loss (RL) of −30.80 dB (99.9% microwave absorption) at the frequency of 14.2 GHz, and the highest total shielding effectiveness achieved is −18.3 dB at 16.8 GHz at 4.38 μm film thickness. The thin films exhibit excellent microwave absorption ability at low thicknesses, and the effective absorption bandwidth (RL < –10 dB) attains a high value of 2.2 GHz in the frequency range of 13–15.2 GHz. These findings can help researchers to enhance the EM wave absorption characteristics in a broad frequency region using lightweight intrinsically conducting polymers.

Conducting Polymeric Composites Based on Intrinsically Conducting Polymers as Electromagnetic Interference Shielding/Microwave Absorbing Materials—A Review

“…The outstanding behavior was attributed to the compact and dense globular morphology observed for this sample. In another study, PPy thin film with 4.38 µm thickness deposited onto alumina coupons was prepared with different Py concentration, without protic acid [84]. The highest EMI SE of 19 dB was observed in the Ku-band frequency region for the sample prepared with 0.2 M of monomer concentration.…”

“…Thin films based on neat ICP layers were also produced by in situ polymerization of the monomer on appropriate substrates. For example, PPy films with good MA properties and EMI SE were obtained through the in situ polymerization of Py on an alumina substrate [82][83][84]. PPy.H 2 SO 4 prepared with ammonium peroxydisulfate (APS) as oxidant with thickness of 1.5 µm displayed EMI SE value of around 10 dB at around 9.2 GHz [82].The same research group used a similar approach for studying the effect of different oxidants as APS, ferric chloride (FeCl 3 ) and potassium persulfate (K 2 S 2 O 8 ) [83].…”

Synthesis and Characterization of Ba0.6Sr0.4Fe12O19/LaMnO3 Composites as Microwave Absorbers

“…The ability of a material to absorb electromagnetic waves is usually referred to as the reflection loss of electromagnetic radiation, RL (dB), calculated by the following equation: [21][22] RL(dB)= 20 log|(Zin -Z0 )/(Zin+Z0 | (3) where Zin and Z0 represent the characteristic impedance of the material and the characteristic impedance of vacuum, respectively. The Zin value is obtained from the equation: Z_in= (μr/εr ) (1/2) tanh[j(2πfd/c) (μr εr ) (1/2) ] ( where µr and ℇr are the relative permeability and permittivity of the material, d is the thickness of the sample, c is the speed of electromagnetic waves in a vacuum, and f is the frequency with which the waves arrive.…”

Fe3O4@PA6/MWCNT composites with multiple gradient segregated structures for electromagnetic shielding with low reflection

“…Microscopically, the material can be designed into core shells, doughnuts, corals, and other structures. 22,26,27 Macroscopically, multilayer structures with different electrical conductivity and electromagnetic wave absorption capabilities can be constructed. 9,[28][29][30][31] On the one hand, through the optimized design of these structures, it is beneficial for electromagnetic waves to enter the material's interior.…”

“…Another solution to reduce the reflection of electromagnetic waves is to optimize the structure of the material. Microscopically, the material can be designed into core shells, doughnuts, corals, and other structures 22,26,27 . Macroscopically, multilayer structures with different electrical conductivity and electromagnetic wave absorption capabilities can be constructed 9,28–31 .…”