Facile Synthesis of Polyindole/Ni_1–xZn_xFe₂O₄(x= 0, 0.5, 1) Nanocomposites and Their Enhanced Microwave Absorption and Shielding Properties

Abstract

The present work reports the fabrication of polyindole (PIN)/Ni 1– x Zn x Fe 2 O 4 ( x = 0, 0.5, 1) nanocomposites as efficient electromagnetic wave absorbers by a facile in situ emulsion polymerization method for the first time. The samples were characterized through Fourier transform infrared spectroscopy, UV–vis spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, high-resolution transmission electron microscopy, and vibrating sample magnetometry. The resulting polyindole/Ni 1– x Zn x Fe 2 O 4 ( x = 0, 0.5, 1) nanocomposites offer better synergism among the Ni 1– x Zn x Fe 2 O 4 nanoparticles and PIN matrix, which significantly improved impedance matching. The best impedance matching of Ni 1– x Zn x Fe 2 O 4 /polyindole ( x = 0, 0.5, 1) nanocomposites was sought out, and the minimum reflection loss of the composites can reach up to −33 dB. The magnetic behavior, complex permittivity, permeability, and microwave absorption properties of polyindole/Ni 1– x Zn x Fe 2 O 4 ( x = 0, 0.5, 1) nanocomposites have also been studied. The microwave absorbing characteristics of these composites were investigated in the 8–12 GHz range (X band) and explained based on eddy current, natural and exchange resonance, and dielectric relaxation processes. These results provided a new idea to upgrade the performance of conventional microwave-absorbing materials based on polyindole in the future.

Adsorption of uranium (VI) from aqueous solutions using boron nitride/polyindole composite adsorbent

“…The peaks at 3420, 1615, and 738 cm −1 were observed due to N–H stretching, N–H and benzene ring deformations, respectively 35 . The peaks at 1454 and 1575 cm −1 belong to the stretching vibrations of C–C bonds in PIn benzene rings 36 . The peak at 1383 cm −1 corresponded to the C–N vibration bonds.…”

“…35 The peaks at 1454 and 1575 cm À1 belong to the stretching vibrations of C-C bonds in PIn benzene rings. 36 The peak at 1383 cm À1 corresponded to the C-N vibration bonds. The peak around at 1708 cm À1 was assigned to carbonyl stretching vibrations of pyrrole ring (N-C=O).…”

Reaction Induced Conformational Change in Polyindole: Polyindole/PVA Film as Biomimetic Sensors of Temperature and Electrical Energetic Conditions

“…The redox reaction of the film was studied using the cyclic voltammogram which shows two‐step oxidation (anodic peak) and corresponding reduction (cathodic peak) of the polymer. The first anodic peak at 0.24 mV represents the ejection of an electron from the polymer chain by the force generated by the applied potential that generates a π conjugated polaronic radical cationic structure [25,36] . The electronic energy level of the electron in the polymer chain was continuously changed by applying potential and the electron was ejected at its ionization potential which is a pH‐independent process.…”

“…The second stage of weight loss corresponding to the removal of low molecular weight oligomers were observed between 190 °C to 305 °C. The polymer chain degradation was obtained between the temperature ranges of 408 °C to 578 °C [36] . It can be observed from the figure that a two‐step weight losses have occurred in the case of bare PVA film.…”

“…The first anodic peak at 0.24 mV represents the ejection of an electron from the polymer chain by the force generated by the applied potential that generates a π conjugated polaronic radical cationic structure. [25,36] The electronic energy level of the electron in the polymer chain was continuously changed by applying potential and the electron was ejected at its ionization potential which is a pH-independent process. The second anodic peak represents the complete oxidation of the polymer chain by the removal of the H + ion from the chain; a pHdependent process.…”