Effect of Doping with Nickel Ions on the Electrical Properties of Poly(aniline-co-o-anthranilic acid) and Doped Copolymer as Precursor of NiO Nanoparticles

Poly(aniline-co-o-anthranilic acid) (PANAA) and its nickel composite (PANAA-Ni) are successfully prepared based on oxidative chemical polymerization via two comparative in situ and ex situ polymerization methods. PANAA copolymer contains aniline, and o-anthranilic acid moieties, were doped with different concentrations of nickel ions. The ratios of aniline, o-anthranilic acid, and nickel chloride were (1:1:0.5) and (1:1:1), respectively. The effect of nickel moiety on the properties of polyconjugated polymers, and their spectral characteristics (UV-Vis absorption spectra, FTIR, thermal stability) were recorded. TGA analysis confirmed that the poly(aniline-co-o-anthranilic acid)/nickel (PANAA-Ni) composites, which were prepared by in situ or ex situ polymerization method, are more thermally stable than the pure PANAA copolymer. The XRD revealed that the pure and PANAA-Ni (prepared by ex situ polymerization method) is completely amorphous structure, while the PANAA-Ni composite (prepared by in situ polymerization method) is a mixture of crystalline and amorphous phases. The temperature dependence of dielectric constants (epsilon(r) and epsilon(i)) as well as AC conductivity (sigma(ac)) were investigated in the temperature range of 300-383 K and test frequency range of 0.1-100 kHz. All the tested samples showed semiconductor behavior. The values of thermal activation energies Delta E1 and Delta E2 for PANAA copolymer are calculated, and found to be in the range of 0.03-0.1 eV and 0.58-1.88 eV, respectively. We calculated Delta E1 and Delta E2 for PANAA-Ni composite, and we found their values in the range of 0.14-0.27 eV and 0.41-0.58 eV, respectively. Moreover, Nanocrystalline nickel oxide NiO powder was prepared by thermal decomposition route of (PANAA-Ni) composites, which was prepared by in situ polymerization method. The size of the obtained nickel oxide nanoparticle was determined by transmission electron microscope .