Surface modification of FePO4 particles with conductive layer of polypyrrole (original) (raw)
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Synthetic Metals, 2011
Conducting polypyrrole/␣-ferric oxide (PPy-Fe 2 O 3 ) composites have been prepared using chemical oxidative polymerization with different weight percentages of ␣-ferric oxide (10-30 wt.%) dispersed during polymerization of pyrrole. These composites were characterized by FT-IR, X-ray diffraction, conductivity and scanning electron microscopy. Four-probe method was used to study the effect of doping on DC-conductivity of the composites. The dispersion of ␣-Fe 2 O 3 in these composite imparts good structural and electrical properties in PPy. The percolation threshold for conductivity was found to be 10% of ␣-Fe 2 O 3 contents in PPy. It arises from an enhanced homogeneous morphology, increase in crystallinity, particle size and shortening of conjugation chain length as confirmed by the scanning electron microscopy, X-ray diffraction and FT-IR analysis.
Synthetic Metals, 2004
The conducting composites were prepared by chemical oxidative polymerization using pyrrole and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) or sulfonated-poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) in chloroform. The pyrrole was protonated and polymerized using iron(III) chloride (FeCl 3). The electrical conductivities of PPy/SPPO composites were increased up to 1 order with the amount of PPy compared to PPy/PPO composites. The introduction of sulfuric group to PPO results in the Coulombic interaction between each phase of composites. As a result, the electrical conductivities might be increased due to the effect of miscibility between each phase. The electrical conductivity of PPy/SPPO composite was increased up to 2.14 S/cm with amount of 25 wt.% PPy. The performance of charge-discharge of PPy/SPPO electrode was much higher than that of PPy/PVdF electrode because SPPO act as a dopant as well as a binder.
Conductivity measurements of electrodeposited polypyrrole
Journal of Applied Electrochemistry, 1987
Thick, freestanding, flexible films of polypyrrole have been prepared from propylene carbonate solutions of pyrrole monomer containing tetra-ethyl ammonium p-toluene sulphonate electrolyte. The conductivity of the films was found to vary with orientation of the sample, deposition temperature and time. Conductivities of up to 338.4 S cm-1 were attained with samples prepared at 0~ XRD analyses have revealed a difference in structure with sample orientation which affects the conductivity of the material significantly.
In-situ polymerization of pyrrole was carried out withtantalum pentoxidein the presence of oxidizing agent i.e. ammonium per sulphate to synthesize polypyrrole/tantalum pentoxidecomposites (PPy/Ta2O5) by chemical oxidation method. The PPy/ Ta2O5composites have been synthesized with various compositions viz., 10, 20, 30, 40 and 50 wt. % of Ta2O5 in pyrrole. The PPy/Ta2O5 composites were characterized by employing Powder X-ray Diffraction (XRD) Spectrometer and Fourier Transform Infra-Red Spectroscopy (FTIR). The surface morphologies of the composites were studied by Scanning Electron Microscopy (SEM). The D.C.conductivities were studied in the temperature range from 30°C– 200°C. The dimensions of tantalum pentoxideparticles in the matrix have a greater influence on the conductivity values.
Polypyrrole-Fe2O3 Nanocomposites with High Dielectric Constant: In Situ Chemical Polymerisation
Polymers and Polymer Composites, 2018
Novel nanocomposites of polypyrrole (PPy) dispersed with iron oxide (Fe2O3) particles have been synthesised by in situ chemical oxidative polymerisation of pyrrole in the presence of ammonium persulfate (APS) as an oxidising agent. The concentration of Fe2O3 was varied between 10-50wt% of PPy. The simultaneous polymerisation of pyrrole and oxide addition led to the complete synthesis of nanocomposites. A maximum dielectric constant of ∼28500 was observed at 20wt% of Fe2O3. The nanocomposites were characterised by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD analysis confirmed the structure and crystallinity of the nanocomposites, and a strong interaction between PPy and Fe2O3 particles was observed by FTIR technique. SEM and TEM images showed that Fe2O3 particles had been coated with PPy by establishing a network during the polymerisation process. The values of dielectric c...
Electrochemical activity of chemically deposited polypyrrole films
Journal of Solid State Electrochemistry, 2003
Conducting polypyrrole (PPY) films are deposited on platinum by chemical oxidation of pyrrole from acid solutions of H 2 O 2 , K 2 S 2 O 8 , K 2 Cr 2 O 7 , FeCl 3 and Fe 2 (SO 4 ) 3 . Cyclic voltammograms and charge-potential data are obtained for these PPY films in 0.1 M LiClO 4 and 0.1 M Na 2 SO4 solutions. Chemically deposited PPY films are electrochemically active and yield oxidation-reduction peak potentials that are similar to those of PPY films electrochemically synthesized in solutions with the same anions. The shape of the cyclic current-potential curves and the charge-potential responses of the chemically deposited PPY depend on the bath composition. The bath determines the counter anion introduced into the PPY film. The physical appearance and thickness of a film depends on the deposition time, acidity and composition of the electroless plating baths.
The electrical properties of conducting polymers make them useful materials in a wide number of technological applications. In the last decade, an important effect on the properties of the conducting polymer when iron oxides particles are incorporated into the conductive matrix was shown. In the present study, films of polypyrrole were synthesized in the presence of magnetite particles. The effect of the magnetite particles on the structure of the polymer matrix was determined using Raman spectroscopy. Mass variations at different concentrations of Fe 3 O 4 incorporated into the conducting matrix were also measured by means of quartz crystal microbalance. Additionally, the changes in the resistance of the films were evaluated over time by electrochemical impedance spectroscopy in solid state. These results show that the magnetite incorporation decreases polymeric film resistance and Raman experiments have evidenced that the incorporation of magnetite into polymeric matrix not only stabilizes the polaronic form of the polypyrrole, but also preserves the polymer from further oxidation.
An Electrochemical Study of Bulk and Nanowire Morphologies of Electrodeposited Polypyrrole
ECS Transactions
Pyrrole was electrochemically polymerised onto gold electrodes at a fixed potential of 0.80 V vs. SCE to generate polypyrrole (PPy). Depending on the pH of the solution, PPy, was deposited in either a bulk or nanowire conformation. Electrochemical impedance spectroscopy, EIS, experiments were subsequently carried out on a bare gold electrode, PPy nanowires and bulk PPy of two different film surface areas. The impedance data were analysed using equivalent circuits giving information on the electrochemical properties of the polymers. The influence of different electrolytes on the impedance was also examined.