Electrical Conductivity Of Polypyrrole Research Articles

Effect of Oxidant/Monomer Ratio on Conductivity of Ferric Chloride Oxidized Polypyrrole

A series of polypyrrole samples were synthesized by oxidizing pyrrole in the aqueous medium of ferric chloride, and the relation between oxidant/monomer ratio and the electrical conductivity of polypyrrole was studied by increasing the ratio from 0.25:1 to 2.5:1. Our results showed that the conductivity of polypyrrole was dependent on the mole ratio of the oxidant to pyrrole, and a maximum value for electrical conductivity of 1500 S/m was achieved for a ratio of 0.75:1.

Effects of Reaction Sequence on the Colloidal Polypyrrole Nanostructures and Conductivity

The relationship between nanoscaled morphology and macroscopic electrical conductivity of polypyrrole (PPy) nanostructures was qualitatively investigated. The PPy nanostructures were prepared via microemulsion polymerization using ionic surfactants. The morphology of PPy was influenced by both the type of ionic surfactants and reaction sequences; specifically, the PPy structures were highly influenced by the reaction sequence when anionic surfactant of SDS was used. By changing reaction sequence, a gel-like PPy was formed influencing on the macroscopic electrical conductivity. The results indicate that the macroscopic conductivity of PPy is affected by its nanoscaled structures as determined by the reaction conditions.

Electrical Conductivity of Polypyrrole–Polymethylmethacrylate Composites Determined by Impedance Spectroscopy

ABSTRACT Thermal properties of polypyrrole–polymethylmethacrylate (PPy–PMMA) composites are analyzed by differential scanning calorimetry (DSC). A decrease in the glass transition temperature Tg with the PPy concentration content reveals the increase of segmental motion. The ac conductivity of these composites is studied in frequency range of 600 Hz to 1 MHz and temperature interval 23°C to 110°C. The study depending on the frequency has highlighted three domains: at low frequencies the conductivity is independent of frequency; at intermediate frequencies, the ac conductivity follows a power law in frequency; and at high frequency the ac conductivity can be explained in terms of hopping process.

Effect of Oxidant/ Monomer Ratio on the Electrical Properties of Polypyrrole in Tantalum Capacitors

In this work, the relation between oxidant/monomer ratio and the electrical conductivity of polypyrrole was studied using different ratios. We achieved a maximum value for electrical conductivity of 7.5 S/cm for a ratio of 2:1. We also developed a chemical dip-coating process to produce the cathode layer in tantalum capacitors. We obtained capacitances of about 80 µF after 8 cycles using the sequence Monomer/Oxidant.

Effect of synthesis parameters on the electrical conductivity of polypyrrole‐coated poly(ethylene terephthalate) fabrics

AbstractThe effects of pyrrole, anthraquinone‐2‐sulphonic acid (AQSA) and iron(III) chloride (FeCl3) concentrations, reaction time and temperature on the electrical conductivity of polypyrrole (PPy)—coated poly(ethylene terephthalate) (PET) fabrics were investigated. With an increase in both the AQSA and FeCl3 concentrations, resistivity decreased to a point beyond which higher concentrations led to increased surface resistivity. Erosion of the polymer coating, in dynamic synthesis from continual abrasion, manifested as an exponential increase in the resistance of the coated textile substrate. This was not encountered in static synthesis conditions. Temperature affected the degree of surface and bulk polymerisation. The effect of polymerisation temperature on conductivity was negligible. Conductive polymer coating on textiles through chemical polymerisation enabled a smooth coherent film to encase individual fibres, which did not affect the tactile properties of the host substrate. The optimum FeCl3/pyrrole and AQSA FeCl3/pyrrole molar ratios were found to be 2.22 and 0.40 respectively. Copyright © 2003 Society of Chemical Industry

Evolution of Physical and Electrochemical Properties of Polypyrrole during Extended Oxidation

The charge storage capacity and electrical conductivity of polypyrrole are followed through regimes of chemically reversible and irreversible electroactivity. Overoxidation of polypyrrole occurs at potentials in excess of 0.7 V vs. a saturated calomel electrode (SCE), as demonstrated by cyclic voltammetry of thin films. Material loss from polymer films as they are overoxidized is determined by in situ quartz microbalance experiments. The potential window for reversible electrochemistry in polypyrrole is compared to that for other conducting polymers. Reflectance FTIR of thick films reveals that hydroxyl groups, followed by carbonyls, result from overoxidation.

Polypyrrole grown at the surface of sulfonated polyethylene films. Electrical conductivity and stability

New data on the electrical conductivity of polypyrrole (PPy) grown at the surface of sulfonated polyethylene (SPE) thin films and its stability in air are presented. The influence of the sulfonation degree of PPy-SPE samples and that of pyrrole polymerization time on conductivity levels have been investigated. It is shown that the conductivity derived using the thickness of the conductive surface layer from infrared transmission spectra of PPy-SPE films allows a convenient definition of the percolation transition observed for the electrical conductivity in these materials. The level of electrical stability of PPy involving sulfonic groups is discussed in the light of conductivity data for PPy containing other different counterions.

Evaluation of electrical conduction in iodine-doped polypyrrole

Electrical conductivity of polypyrrole has been measured after doping with different iodine concentrations. A thermally activated electrical conductivity was found which was pseudoohmic and increased with doping level. The results can also be fitted by log σ versusT−1/2 and log σ versusT−1/4 dependences, instead of the Arrhenius log σ versusT−1 dependence. From these results it was concluded that within the experimental scatter no significant distinction can be made between these different temperature dependence laws. Hence these data can only enable one to speculate about the true underlying transport model, rather than to draw decisive conclusions. Electrical conductivity results predicting the role of iodine dopant concentration on the conduction process of semiconducting polypyrrole are discussed.