Polyaniline-Graphene nanoplatelet composite films with improved conductivity for high performance X-band microwave shielding applications

Novel nanocomposite systems of para-Toluene Sulphonic Acid (p-TSA) doped Polyaniline (PANI) - Graphene nanoplatelet (GRNP's) composite films (of thickness similar to 1.5 mm) were prepared by in situ polymerization of aniline in the presence of Graphene nanoplatelets. Structural and morphological features of the prepared films were characterized by various analytical techniques such as Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red Spectroscopy (FTIR), X-ray diffraction (XRD), Raman Spectroscopy and Thermogravimetric Analysis (TGA). The presence of GRNP's in the PANI matrix has significantly improved the conductivity and dielectric properties of the composites due to the formation of 3D conducting networks. Shielding effectiveness of the PANI-GRNP's composite films doped with p-TSA was examined by using S-parameters obtained from vector network analyzer in the X-band microwave frequencies. The shielding efficiency of the composites shows a strong dependence on GRNP's content in the PANI matrix. The in situ polymerization of aniline diffused into Graphene nanosheets leads to enhanced interfacial polarization due to solid state charge transformation between PANI and GRNP's and contributes to higher microwave absorption. The PANI-GRNP's composite with 10 wt% of GRNP's in PANI matrix shows excellent shielding efficiency ( > 95%) in the X-band frequencies. The results indicate that, contribution to overall Electromagnetic Interference Shielding Effectiveness (EMI SE) in the composites is due to dominant absorption mechanism. Due to low cost, light weight, better thermal stability, improved conductivity and excellent EMI SE properties, these composites can be promising materials for electromagnetic shielding applications in X-band microwave frequencies.