Nanocomposites and nanomaterials

Structure and properties of polyaniline nanocomposites with noble metals
O. Aksimentyeva, Yu. Horbenko, Ya. Koren, P. Demchenko
Ivan Franko National University of Lviv, 6/8 Kyryla&Mefodia , 79005, Ukraine; E-mail: y_bilka@ukr.net

Conducting polymer and noble metal nanoparticle hybrids have attracted the most intensive attention in the past few years due to the synergistic effects between individual components that contribute to the increased performances in diverse applications such as electronics, photonics, catalysts, nano and biotechnology [1,2]. In view of its environmental stability, low cost, ease of synthesis, polyaniline (PAn) is the most intensively investigated among the conjugated polymers [2].
The aim of this work was to study the influence of the nature of the noble metal (Ag, Au, Pt, Pd) on the synthesis and structure of composites with PAn. Samples have been obtained in the conditions of emulsion polymerization during which the ions of the metal are recovered, due to the change in the oxidation degree of the newly formed polymer chains, and form nanosize particles. By X-ray structural studies and scanning electron microscopy with energy-dispersive spectroscopy it has been showed that the formation of uniformly distributed metallic grains with the size of 12.6 ± 3.4 nm in the polymer is characteristic for PAn-Au composite. In the case of PAn-Ag composite the main mass of metal is included in the polymer matrix and an average particle size is 30.5±3.5 nm. The diffractogram of the PAn-Pt composite has only amorphous halo, which is inherent to the polymer, whereas the energy-dispersion spectroscopy indicates the presence of metal in the composite. Obviously, Pt is in completely amorphous state (the size of the particles of its phase grains is ~2 nm). Separate sections of the metallic phase have not been recorded on the CEM images, which suggests the formation of chemical compounds. Consequently, Pt and Pd are included in the polymer chain covalently or in coordination with the polymer ligands. Au and Ag enter the composite in the form of nanoparticles uniformly distributed in the polymer matrix. Depending on the nature of the inclusion of the metal in the polymer matrix, the metal center affects both the type of bond and the degree of polymerization.

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