EMI shielding and microwave absorption behavior of Au-MWCNT/polyaniline nanocomposites

Abstract

Electrically conducting Au-multiwalled carbon nanotube/polyaniline (Au-MWCNT/PANi) nanocomposites were synthesized by two different ways: (1) by direct mixing of MWCNT/PANi and Au nanoparticles (Au-MWCNT/PANi-1) and (2) by in situ polymerization of aniline in the presence of both MWCNTs and Au nanoparticles (Au-MWCNT/ PANi-2). The higher electrical conductivity of Au-MWCNT/PANi-2 compared with the other samples (PANi, MWCNT/PANi, Au-MWCNT/PANi-1) is supported by the red shifts of the UV-vis bands (polaron/bipolaron), the high value of the -NH+= stretch peak (Fourier transform infrared spectroscopy studies), the high % crystallinity (X-ray diffraction analysis) and more uniform dispersion of the Au NPs in the material. The performance of the samples in electromagnetic interference (EMI) shielding and microwave absorption was studied in the X-band (8-12 GHz). For all the samples, absorption was the dominant factor contributing toward the EMI shielding. Au-MWCNT/PANi-2 showed the best performance with a total shielding effectiveness of À16 dB [averaged over the X-band (GHz)] and a minimum reflection loss of À56.5 dB. The higher dielectric properties resulting from the heterogeneities because of the presence of nanofillers and the high electrical conductivity lead to the increased EMI shielding and microwave absorption. The results show the significance of both Au nanoparticles and method of synthesis on the EMI shielding performance of MWCNT/PANi composites. Figure 3. TEM images of MWCNTs (a), MWCNT/PANi (b), Au-MWCNT/PANi-1 (c) and (d) and Au-MWCNT/PANi-2 (e) and (f).Figure 7. FTIR spectra of different samples.Figure 6. UV-vis spectra of aqueous Au colloid (a); PANi and PANi composites in DMSO (b).Figure 12. Loss tangent (a) and skin depth (b) of PANi and its composites in the frequency range of 20 Hz-2 MHz.

MnO2‐Magnetic Core‐Shell Structured Polyaniline Dependent Enhanced EMI Shielding Effectiveness: A Study of VRH Conduction

“…The doublet observed in the range of 1400 to 1600 cm −1 is the characteristic band of conducting state of PANI/MnO 2 composite, wherein the band observed at∼1561 cm −1 is attributed to quinoid ring stretching vibrations, whereas, the band observed nearly at 1470 cm −1 is ascribed to benzenoid ring stretching vibrations. The change in the intensity of these bands is associated with change in electrical conductivity and the conjugation length . Another doublet observed at the lower wavenumber having two sharp reflections at ∼1295 and 1240 cm −1 , which are associated with the N−H band bending vibrations and C−N asymmetric stretching mode of benzenoid rings.…”

“…These desires of the scientists are fulfilled with the development of polymeric materials, but scholars still come across with an impediment of generation of static charge. This problem of development of static charge on the surface of insulating polymers is circumvented with the growth of conducting polymer, which satisfy almost all the basic requirements of shielding materials . However, the metallic materials having higher shielding effectiveness (∼40‐100 dB), achieved via the reflection phenomenon of electromagnetic radiations as compared to intrinsic conducting polymers (∼50‐60 dB), using both the absorption as well as reflection phenomena for EMI shielding .…”

“…This problem of development of static charge on the surface of insulating polymers is circumvented with the growth of conducting polymer, which satisfy almost all the basic requirements of shielding materials . However, the metallic materials having higher shielding effectiveness (∼40‐100 dB), achieved via the reflection phenomenon of electromagnetic radiations as compared to intrinsic conducting polymers (∼50‐60 dB), using both the absorption as well as reflection phenomena for EMI shielding . But the conducting polymeric materials are advantageous in several aspects as discussed above in addition to the absorbing ability of polymeric materials through which EM radiation are substantially eliminated from the environment, which are persisted in environment in case of metallic shielding materials due to sole reflection phenomenon.…”

An Ingenious Strategy to Construct Helical Structure with Excellent Electromagnetic Shielding Performance

“…Furthermore, FWHM of NaCF/PANI and CF/PANI is 1.13° and 1.19°, respectively. The smaller FWHM indicates a more compact and ordered molecular arrangement in NaCF/PANI, which can facilitate intermolecular hopping of charge carriers and intramolecular electron transfer . These two factors are important for improving electrical conductivity.…”

Review of Polymer Composites with Diverse Nanofillers for Electromagnetic Interference Shielding

“…For the SE a frequency range of 8 to 12 GHz has been used. The composite with improved properties has shown a SE of 16 to 56 dB, and the absorption as the primary mechanism of shielding [119].…”