Conductive Polypyrrole/Tungsten Oxide Metacomposites with Negative Permittivity

Abstract

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

Influence of the Incorporation of CeO2 Nanoparticles on the Ion Exchange Behavior of Dodecylsulfate Doped Polypyrrole Films: Ac-Electrogravimetry Investigations

“…In a nonexhaustive list, one can remind that polypyrrole/WO 3 nanomaterials based composite materials possess a rare negative permittivity and their switching frequency can be tuned with the help of particle loading. In particular, among other parameters, increased nanoparticle loading was also shown to improve the electrical conductivity, dielectric permittivity, and thermal stability of the resulting nanocomposites [7]. One should also notice that magnetite incorporation stabilizes the polaronic form of polypyrrole matrices and also preserves it from further oxidation [8] or allows production of unexpected 1 µm wide stripe-like microstructures resulting from the self-assembly of magnetic components [9].…”

Fabrication and evaluation of thin layer PVDF composites using MWCNT reinforcement: Mechanical, electrical and enhanced electromagnetic interference shielding properties

“…Looking into various reports [20][21][22][23][24][25][26][27][28] on materials done earlier, the underneath science was understood. Similar system, such as of PVDF/MWCNT has been studied by G.S.…”

“…[18][19][20][21] Change in ε ′ (and further Tan δ) from positive to negative after percolation threshold is due to induction polarization. [23][24][25][26][27] To further evaluate the SE data for all samples and to check whether the high SE is due to reflection and /or absorption, the raw data was again looked into. It was found that, with the incorporation of various wt% of MWCNT in the PVDF, the absorption parameter increased concomitantly in the 5 wt% sample and above, as compared to the reflection contribution.…”

Fabrication and capacitive characteristics of conjugated polymer composite p-polyaniline/n-WO3 heterojunction

“…Polymer nanocomposites (PNCs) based on conjugated polymers (CPs) including polythiophene [1,2] polypyrrole (PPy) [3,4], poly(DNTD) [5,7], polyaniline (PANI) [8,9] and their derivatives have attracted huge attention. The methodology for combining CPs and inorganic materials has announced PANI because of its fascinating properties such as facile polymerization in aqueous media [10][11][12][13] or nonaqueous media [14], versatile redox behavior, good stability in air, low cost, high conductivity and high pseudocapacitance [15,16].…”