Magnetization and thickness dependent microwave attenuation behaviour of Ferrite-PANI composites and embedded composite-fabrics prepared by in situ polymerization

Ultrahigh efficient and effective electromagnetic-interference (EMI) shielding composites have been fabricated with the combination of Polyaniline and zinc-cobalt ferrites (Co1-xZnxFe2O4, 0.1 ≤ x ≤ 0.4). Ferrite nanoparticles synthesized via the sol-gel method were functionalized to polyaniline via in situ polymerization. Average crystallite sizes of the nanoparticles were estimated using Debye–Scherrer and Rietveld method and found to be in between 20-30 nm. FTIR spectra revealed the formation of interactions between the PANI molecules and the ferrite nanoparticles. Substitution of the nonmagnetic Zn ions considerably changes the magnetic properties of cobalt ferrites as observed from the M-H loops recorded by VSM at room temperature. The EMI-shielding performance of the fabricated composites was examined at various thicknesses with the polymer filler ratio of 1:1 in X-band frequency region using a vector network analyser. The EMI shielding performance of composites was found to be increasing with the thickness of composites where a thickness of 3.0 mm achieved an SE of ∼ 100 dB for the Co0.7Zn0.3Fe2O4-PANI composite. Composite absorbers were deposited on cotton fabrics for protective clothing by in situ incorporation during the synthesis of composites which displayed relatively high EMI shielding effectiveness (SE) (40-45 dB) at a thickness of only 0.30 mm for the fabrics. The PANI-Ferrite nanocomposites can be established as promising high capacity electromagnetic shielding materials because of the dipole polarization and the magnetic losses with low cost, lightweight, high durability and good flexibility.