Preparation and characterization of polyaniline-based magnetic nanocomposites for EMI shielding applications

Among the wide applications of polymers, their use to reduce electronic noise is receiving great attention from the scientific and technological communities. This electronic noise is part of electromagnetic interference (EMI), which is responsible for the degradation of electronic systems or their interference with other electronics devices. The uncontrolled exposure to electromagnetic waves caused by the problems mentioned before can also be conducive to health concerns. Polyaniline (PAni) characteristics of frequency agility, light weight, simple tuning of functional properties and its non-corrosive nature, make this polymer a suitable material for the development of electromagnetic shielding materials where protection against noise without degradation of device performance is the main aim. Tuning of conductive and magnetic properties in PAni-based nanocomposites can be achieved by suitable selection of polymerization conditions and controlled addition of ferrites nanoparticles.; PAni was synthesized by polymerization of aniline in presence of ammonium peroxydisulfate and HCl. The disperse phase consisted of low-coercivity (Zn-Mn ferrites) nanoparticles. Our work was focused on the synthesis of PAni matrix and the ferrite disperse nano-phase as well as the determination of suitable conditions for homogeneous dispersion of the nanoparticles during the polymerization process in order to achieve suitable homogeneity of the magnetic properties in the final composites. The results of magnetic characterization by Vibrating Sample Magnetometer (VSM) magnetometers, and structural and morphological characterization by X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), Scanning Electron Microscope (SEM), High Resolution Transmission Electron Microscopy (HRTEM) techniques respectively, are presented and discussed. The effect of the presence of ferrite nanocrystals on the thermal stability of the nanocomposites has been evaluated by Thermogravimetric analyses (TGA) of the composites produced at different PAni/ferrite molar ratios. The conductivity of synthesized PAni-based nanocomposites has also been calculated from Current Vs Voltage (I Vs V) measurements carried out at room temperature conditions.