Electrical, Sensing and Thermal properties of Polypyrrole (original) (raw)
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Thermal, electrical and sensing properties of polypyrrole/tin oxide nanocomposite
Ferroelectrics, 2018
Polypyrrole/Tin oxide nanocomposites were synthesized by in-situ polymerization methods. The prepared nanocomposites were characterized by Scanning electron microscopy (SEM), Transmission Electron Microscope (TEM) and studied its Thermal properties like Differential Scanning Calorimeter (DSC). The dc conductivity of the samples was measured as a function of temperature in the range 30-190 C and it was found that the increasing the concentration of SnO 2 nanoparticles increases the conductivity due to the hopping of polarons and extended chain length of composites. Among all nanocomposites, 30% showing highest conductivity and sensitivity so from the study it is suggested that these nanocomposites are useful in potential applications.
Effects of preparation temperature on the conductivity of polypyrrole conducting polymer
Journal of Chemical Sciences, 2002
An attempt has heen made to investigate the effect of temperature on the conductivity of polypyrrole conducting polymer films prepared by an electrochemical method in an aqueous medium using camphor sulfonate as the dopant. The polymer was grown from aqueous solutions employing a range of temperatures (l–60°C). It was found that with increase in temperature the conductivity decreased and the
Electrical Conductivity of Polypyrrole Films at a Temperature Range of 70 K to 350 K
Materials Research Bulletin, 1998
The dc conductivity of electrochemically synthesized polypyrrole films doped from light to intermediate levels with p-toluene sulfonic acid was measured in the temperature range of 77 to 300 K, using a modified four-probe rig. Plots of dc conductivity vs. temperature were parameterized by fitting Mott's Variable Range Hopping conduction model. The localization length of localized electrons was assumed to be 3 Å, which is approximately equal to the length of a pyrrole monomer. Mott parameters of polypyrrole films doped with p-TS were evaluated at 300 and 10 K. Results were found to be consistent with Mott's requirement that ␣R Ͼ Ͼ 1. Microwave (10 GHz) conductivity measurements were carried out on the same set of polypyrrole samples at a temperature range of 90 to 473 K. Both microwave and dc conductivities were found to increase with temperature. The large values of microwave conductivity compared to dc conductivity over the temperature range tested suggests the existence of more charge hopping that does not contribute to the dc conductivity.
Polymer, 2000
The electrical conductivity of chemically prepared polypyrrole in aqueous solution was found to be strongly dependent on the preparation technique and polymer additive. Owing to the hygroscopic nature of polypyrrole, it is essential to remove residual water. Accordingly, the conductivity can be enhanced by about two orders of magnitude when using a preparation technique that includes a washing treatment with organic solvents and drying under vacuum at elevated temperatures to attain maximum removal of water. Thus, the electrical conductivity of polypyrrole is affected not only by reported factors such as the ratio of oxidant to pyrrole, reaction temperature, and reaction time, but also by the preparation technique. Additionally, a significant enhancement of the conductivity up to 90 S cm Ϫ1 by using of poly(ethylene glycol) as an additive during the polymerization could be achieved. ᭧
Synthesis, characterization, morphological and electrical studies of polypyrrole nanostructures
Nucleation and Atmospheric Aerosols, 2019
Conducting polypyrrole was synthesized by three independent methods such as inverse micro emulsion polymerization (MIP), nano polymerization (Nano PPy) and bulk polymerization (Bulk PPy) and the samples were characterized by FESEM, XRD, FTIR and UV-visible Spectroscopy. DC conductivity studies of the samples were investigated by Keithley two probe method and it was found that polypyrrole by MIP method shows highest dc conductivity value as 5.3672x10-7 Smˉ1 while Nano PPy and Bulk PPy as 1.8911x10-7 and 0.8564x10-7 Smˉ1 respectively. In UV-visible spectroscopy, polypyrrole showed absorption peak at 380nm corresponding to π to π* excitation transition which confirms conjugated polypyrrole structure in all samples with absorbance 0.2809, 0.0861 and 0.6142 for MIP PPy, Nano PPy and bulk PPy respectively. FTIR spectra show maximum absorbance for Bulk PPy. Peak at 1457 cm-1 , 1557 cm-1 (C=C stretching of pyrrole rings), (N-H bending vibrations), 1376 cm-1 and 1300 cm-1 (stretching peaks of C=N and C-N bonds) confirms polypyrrole formation 1. FESEM images of polypyrrole shows spherical morphology for MIP PPy and Bulk PPy while nano PPy possess globular morphology with agglomeration of particles; with particle size in nano range. The peaks obtained for all polypyrrole samples were broad in X-ray diffraction studies confirming its amorphous nature. It also indicates poor crystallinity and short range arrangement of PPy chains.
Thermoelectric power and conductivity of different types of polypyrrole
Journal of Polymer Science Part B: Polymer Physics, 1999
We have measured the thermoelectric power and conductivity as a function of temperature of a wide range of polypyrrole samples, including a film of soluble polypyrrole synthesized chemically, and wrinkled films synthesized using indium-tin oxide electrodes; other samples investigated include high-conductivity polypyrrole films synthesized at different temperatures and current densities, films grown on nonconducting substrates, and polypyrrole gas sensors. The thermoelectric powers are remarkably similar and metal-like for the medium and high conductivity samples but show nonzero extrapolations to zero temperature for wrinkled samples. The temperature dependence of conductivity tends to be greater for samples of lower conductivity. In contrast to polyaniline and polyacetylene, a crossover to metallic sign for the temperature dependence of conductivity at higher temperatures is not observed in any of our samples; the fluctuation-induced tunnelling and variable-range hopping expressions account for nearly all our conductivity data except for low-temperature anomalies.
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.
Structure, strength and electrical performance of conducting polypyrroles
Journal of Materials Science, 1988
Polypyrrole films, typically 0.2 mm thick, were prepared by electrodeposition with p toluene sulphonate as dopant anions. Conductivities of up to 340 S cm -~ were found, comparing favourably with other cited examples. Conductivity along each sample was found to be much greater than across: such asymmetry may be exploitable. Electrodeposition temperatures (0 ° C) lead to higher conductivities than at 25 ° C. The structure was amorphous as indicated by X-ray diffraction, and the morphology was found to be nodular by using optical and scanning electron microscopy. Films were found to be quite strong and tough, although some reduction in mechanical performance was found after ageing in air. Fracture surfaces of tensile test pieces suggest a layered structure, with little evidence for viscous deformation being evident.
A conducting composite of polypyrrole I. Synthesis and characterization
Synthetic Metals, 1994
The success of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry for the characterization of polymer structures and for the determination of average molecular weights and distributions depends on the use of a proper sample/matrix preparation protocol. This work examines the effect of solvents, particularly solvent mixtures, used to prepare polymer, matrix, and cationization reagent solutions, on MALDI analysis. It is shown that the use of solvent mixtures consisting of polymer solvents does not have a significant effect on the molecular weight determination of polystyrene 7000 and poly(methyl methacrylate) 3750. However, solvent mixtures containing a polymer nonsolvent can affect the signal reproducibility and cause errors in average weight measurement. This solvent effect was further investigated by using confocal laser fluorescence microscopy in conjunction with the use of a fluorescein-labeled polystyrene. It is demonstrated that sample morphology and polymer distribution on the probe can be greatly influenced by the type of solvents used. For sample preparation in MALDI analysis of polymers, it is important to select a solvent system that will allow matrix crystallization to take place prior to polymer precipitation. The use of an excess amount of any polymer nonsolvent should be avoided. (J Am Soc Mass Spectrom 1998, 9, 1303-1310
Electrical property and stability of electrochemically synthesized polypyrrole films
Journal of Applied Polymer Science, 2004
Polypyrrole (PPy) films doped with arylsulfonate dopants were prepared by electrochemical polymerization, to investigate the effects of various dopants on conductivities, thermal stabilities, and morphologies of PPy films. Also, HCl was added to those dopants as a cooperating dopant, to improve conductivity of PPy films. Conductivity of PPy film doped with the mixture of each dopant and HCl was improved. Temperature dependency on conductivity for PPy films doped with various dopants was investigated by heating them from 30 to 300°C. For the film doped with TSA, DBSA, and AQSA, conductivity increased up to 150°C and then rapidly decreased, whereas the conductivity of other films decreased after 200°C as temperature increased up to 300°C. Moreover, the film doped with small size dopant such as TSA and HCl/TSA had an interconnected porous fibrillar-like morphology. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3659–3666, 2004