Nanocompósito formado por Polianilina e Óxido De Cobre II: caracterização estrutural e morfológica

Abstract

Nanocomposites are currently studied due to improvements in some properties that they present when compared their constituents. This study proposes the structural and morphological characterization of a nanocomposite based on a polymer matrix formed by Polyaniline Emeraldine-salt form (PANI-ES), reinforced by Oxide Copper II (CuO). Considering the class of Intrinsically Conductive Polymer (ICP), polyaniline is the most studied due to low cost of monomer and ease of synthesis. On the other hand, CuO has been reported in several technological applications. Properties related to the pure materials and in the form of the nanocomposite, for example, the structural, morphological and electrical properties were investigated. Such information is useful to propose possible technological applications for this material. The techniques of X-ray Diffraction (XRD), structural refinement by Le Bail method, Scanning Electron Microscopy (SEM) and Measurement of Electrical Conductivity were performed for characterization of the pure components and for the nanocomposite. XRD technique allowed the visualization of the polymer amorphization in the nanocomposite form, suggesting some kind of interaction between its constituents in interface level. The percentage of crystallinity calculated for the PANI-ES and nanocomposite was estimated at 24% to 38%, respcetively. Le Bail method showed a increasing of unit cell for PANIES in order to accommodate the counter ions inserted in the molecular structure of the polymer during the doping process. The average crystallite size were found around 21 Å for PANI-ES. The CuO showed much larger crystallites, as expected, with an average size of 119 Å. SEM images of PANI-ES showed a well defined nanofiber morphology with ranged size and thickness for pure PANI-ES. This morphology was not observed in the nanocomposite form, confirming the results observed previously by XRD. The morphology of the CuO particles are spherical, resulted from the deposition of nanoplates. SEM images showed that the CuO particles coexist with the polymer matrix. It is possible to verify a lower regularity of PANI-ES nanofibers and high organization of nanoplate that compose the CuO particles, justifying the increasing of crystallinity in the nanocomposite. It is suggested that polymerization of PANI-ES on the CuO particles to form the nanocomposite affected the natural alignment of the polymer chains, impairing ordered molecular arrangement of the polymer. The conductivity measurements of PANIES and nanocomposite were 1,11x10-4 S/cm and 2,77x10-4 S/cm, respectively. Nanocomposite presented 60 times more conductivity than PANI-ES. Thus, through this research, it was possible to determine the structural and morphological properties of the PANI-ES, CuO and PANI/CuO nanocomposite.