Chloride salt of conducting polyaniline synthesized in the presence of CeO2: Structural analysis of the core-shell nanocomposite

Abstract

Chloride salt of conducting Polyaniline (ES-PANI) was synthesized in the presence of cerium dioxide (CeO2) for structural and morphological evaluation of the resulting core-shell nanocomposite. X-ray Diffraction (XRD), estimative of crystallinity percentage, Le Bail Method, Scanning Electron Microscopy (SEM) and DC electrical conductivity were used for materials characterization. The resulting nanocomposite was constituted of three phases as identified by X-Ray Diffraction: ES-PANI, CeO2 and CeCl3(H2O)7, chloride hepta-hydrate cerium. Crystallinity of ES-PANI and nanocomposite were estimated around 40 and 85%, respectively. XRD patterns were also used to perform the Le Bail Method. This refinement allowed structural characterization of each phase, obtainment of cell parameters and crystallite size and shape. For ES-PANI and CeCl3(H2O)7, crystallites showed a prolate-like shape with an average size of 21 Å and 104 Å, respectively. CeO2 crystallites presented much larger size, as expected, with isotropic average size of 490 Å. SEM images showed that the nanocomposite has a core-shell morphology with both ES-PANI nanofibers and CeCl3(H2O)7 particles coating the CeO2 particles. The polymerization of ES-PANI over the CeO2 particles in order to form the nanocomposite affected the natural chain alignment of the polymer, resulting in better molecular rearrangement and larger crystallites. Finally, measurements of DC electrical conductivity of ES-PANI and nanocomposite have showed values of 1.11 × 10−4 and 2.22 × 10−4 S/cm, respectively. Nanocomposite has showed electrical conductivity 50 times greater than the pure ES-PANI. Thus, in this work we have reported a systematic structural and morphological investigation of PANI/CeO2/CeCl3(H2O)7 core-shell nanocomposite.