(763c) Giant Magnetoresistive Phosphoric Acid Doped Polyaniline-Silica Nanocomposites

In this talk, the phosphoric acid doped conductive polyainiline (PANI) polymer nanocomposites (PNCs) filled with silica nanoparticles (NPs) have been synthesized using a facile surface initiated polymerization method. The chemical structures of the nanocomposites are characterized by Fourier transform infrared (FT-IR) spectroscopy. The enhanced thermal stability of the PNCs compared with pure PANI is observed by thermogravimetric analysis (TGA). The dielectric properties of these nanocomposites are studied by LCR meter with equipped with a dielectric test fixture. The electrical conduction mechanism of the synthesized nanocomposite samples is explored by Mott variable range hopping (VRH) law via temperature dependent resistivity analysis. A giant magnetoresistance (GMR) is obtained in the magnetoresistance test and is well explained by wave-function shrinkage model through calculating the changed localization length (a₀), density of states (N(E_F)) at Fermi level and reduced average hopping length (R_hop). The effects of particle size on the properties including thermal stability, dielectric properties, temperature dependent resistivity, electrical conduction mechanism and GMR of the nanocomposites are also studied as well.