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 (8-12GHz). 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 -16dB [averaged over the X-band (GHz)] and a minimum reflection loss of -56.5dB. 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.
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E. J. Jelmy, Ramakrishnan, S., and Dr. Nikhil K. Kothurkar, “EMI shielding and microwave absorption behavior of Au-MWCNT/polyaniline nanocomposites”, Polymers for Advanced Technologies, 2016.