(213c) Conductive Polymer Metacomposites with Sphere- and Rod- Like Nano-WO3

Polypyrrole (PPy) nanocomposites reinforced with tungsten oxide nanoparticles (WO3 NPs) or nanorods (NRs) were fabricated with surface initiated polymerization method. Results show that the electrical conductivity is strongly dependent on the particle loadings, molar ratio of oxidant to pyrrole monomer and filler morphology, the electron transportation in the nanocomposites follows a quasi 3-d variable range hopping (VRH) conduction mechanism as evidenced by the temperature-dependent conductivity function. Unique negative permittivity was observed in both pure PPy and nanocomposites, and the switching frequency (frequency where real permittivity switch from negative to positive) can be tuned by changing the particle loading, ratio of oxidant to pyrrole monomer and filler morphology. The extent of charge carrier localization calculated from the VRH mechanism well correlated to the dielectric properties of the nanocomposites. Results show that WO3 NRs are more efficient in improving the electrical conductivity, dielectric permittivity and thermal stability of the resulting nanocomposites as compared to WO3 NPs. The microstructures of pure PPy and WO3/PPy nanocomposites are observed by scanning electron microscopy. Powder X-ray diffraction analysis demonstrates the crystal structure of WO3 NPs and NRs, as well as their corresponding nanocomposites. Thermogravimetric analysis reveals that the thermal stability of the nanocomposites is significantly enhanced with the addition of nanofillers.

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