Synthesis and characterization of polyaniline-ZnO composite and its dielectric behavior

Films of polyaniline (PANI) and PANI-zinc oxide (ZnO) composites have been synthesized by solution cast and spin coating technique. The ZnO, powder of particle size 100-200 nm was synthesized by sol-gel technique and the polyaniline was synthesized by chemical oxidative polymerization of aniline. The composite films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infra red (FTIR) and the results were compared with polyaniline films. Dielectric properties of PANI and PANI-ZnO composite films have been investigated between frequency ranges of 8.5 and 13.0 GHz. The 'a' lattice parameter of ZnO was found to increase and the 'c' lattice parameter was found to decrease after ZnO-PANI composite formed. The characteristic FTIR peaks of PANI were found to shift to higher wave number in ZnO-PANI composite. These observed effects have been attributed to interaction of ZnO particles with PANI molecular chains. Dielectric constant of PANI-ZnO composite film was found to be smaller than the PANI film. The decrease of dielectric constant in PANI-ZnO films as compared to PANI was attributed to the interfaces formed between ZnO particles and PANI. (C) 2008 Elsevier B.V. All rights reserved.