Chemical synthesis and low temperature electrical transport in polypyrrole doped with sodium bis(2-ethylhexyl) sulfosuccinate (original) (raw)
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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. ᭧
Synthetic Metals, 2004
Polypyrrole (PPy) was synthesized by chemical oxidative polymerization of pyrrole in aqueous solution containing an oxidant, ferric sulfate, ferric chloride or potassium peroxydisulfate. An anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT), was used as an additive. The elemental analysis and FTIR spectroscopy proved that a part of the anionic surfactant was incorporated into PPy similarly like the doping anion. This results in a more compact morphology and reduced sizes of the PPy globules. Furthermore, the addition of AOT to the reaction mixture results in significantly increased conductivity, especially when ferric sulfate was used for pyrrole polymerization. PPy synthesized in polymerization solution containing ferric sulfate and at molar ratio [pyrrole]/[AOT] = 7 reached conductivity as high as 15 S cm −1 , while the same experiment performed in the absence of AOT yielded a product with conductivity of 0.032 S cm −1 only. The conductivity measurement during cyclic thermal treatment of samples showed a stabilizing effect of AOT on conductivity of PPy compared with PPy samples prepared without AOT.
Surface properties and conductivity of bis(2-ethylhexyl) sulfosuccinate-containing polypyrrole
Applied Surface Science, 2005
Polypyrrole (PPy) was chemically synthesized by oxidative polymerization of pyrrole in aqueous solution containing an oxidant, ferric chloride, and an anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The results of elemental analysis confirmed that the surfactant is incorporated into the PPy structure. The presence of the anionic surfactant AOT in polymerization mixture influences the properties of chemically prepared polypyrrole due to bonding the anionic part of the surfactant molecule to the PPy chains as proved by X-ray photoelectron spectroscopy (XPS) analysis. Scanning electron microscopy study showed that the presence of the AOT affects the morphology of the product. A more compact powder morphology and reduced size of the PPy globules were revealed. The addition of AOT to the reaction mixture results in a significantly increased conductivity: PPy synthesized in polymerization solution containing molar ratio [pyrrole]/[AOT] = 7 reached conductivity as high as 27 S cm À1 , while the same experiment performed in the absence of AOT yielded a polymer with conductivity of 3.9 S cm À1 only. #
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 Properties of Polypyrrole Conducting Polymer at Various Dopant Concentrations
Polypyrrole conducting polymer was prepared by chemical reaction method with various concentrations of iron (III) chloride (FeCl3) as dopant. The dc conductivity was obtained from current-voltage characteristic by using parallel-plate techniques in the temperature range of 100-300K. With the involvement of chloride, Cl -in the polymeric chain, the conductivity increased as temperature and the dopant concentration increased. To describe the electrical transport process, Mott's 1-D, 2-D and 3-D variable range hopping (VRH) models have been considered. The result gives evidence of transport mechanism based on Mott's 3-D VRH mechanism for all various dopant concentrations studied.
Transport Properties of Polypyrrole Films Doped with Sulphonic Acids
Bulletin of the Korean Chemical Society, 2009
The polymer blends containing polypyrrole (PPy) and the sulphonic acids such as β-naphthalene sulfonic acid (NSA), camphor sulfonic acid (CSA), and dodecylbenzenesulfonic acid (DBSA) were synthesized by in situ deposition technique in an aqueous media using ammonium per sulfate (APS) as an initiator. The obtained films were characterized by scanning electron microscopy (SEM), and the thermal behavior of these polymer blends was analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The temperature-dependent (DC) conductivity of the obtained films shows a semiconducting behavior with a negative temperature coefficient of resistivity (TCR). The conductivity data were also analyzed through Mott's equation, which provides the variable range hopping model in three dimensions. The parameters such as density of states at the Fermi energy, hopping energy, and hopping distance were calculated for PPy, PPy-NSA, PPy-CSA, and PPy-DBSA films, and the data were compared.
Evaluation of electrical conduction in iodine-doped polypyrrole
Journal of Materials Science, 1992
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 cr versus T -1/2 and tog o-versus T-1/4 dependences, instead of the Arrhenius log cr versus T -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.
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
Synthetic Metals, 2010
Electrical characteristics of polypyrrole films electrodeposited in different aqueous electrolyte solutions including p-toluenesulfonate, naphtalenesulfonate, nitrate, tetrafluoroborate, and perchlorate anions were investigated using the Van der Pauw procedure. The polymer films were synthesized by electrochemical oxidation at a fixed potential. Experimental parameters including the pyrrole concentration, electrolyte, applied potential and substrate were shown to affect the electrical conductivity of polypyrrole films. Since the substrate contributes significantly to the overall conductivity of polypyrrolecoated electrodes, the results obtained with free standing polymer films appeared more reliable. The results indicated that the p-toluenesulfonate doped PPy film showed the highest average conductivity ( 293 K = 4.5 × 10 5 S m −1 ) whereas the perchlorate doped one produced the lowest of all the films prepared ( 293 K = 2 × 10 4 S m −1 ).
Synthetic Metals, 2000
The effects of using dodecylbenzene sulfonic acid as a dopant on electrical conductivity of polypyrrole films were investigated in N 2 atmosphere and SO -N mixtures. For a film with a higher doping level, the time for the specific electrical conductivity s to reach its 2 2 dc Ž . equilibrium value when exposed to SO was reduced; and consistently, the short time response d s rd t at zero exposure time 2 dc increased. The temporal response of conductive polypyrrole films was improved with the films having higher doping levels. On the other hand, the gas sensitivity or change in the specific electrical conductivity from its base value when exposed to SO was independent of 2 dopant concentration, if it was below a critical doping level. Above this critical doping level, the change in the specific electrical conductivity climbed to a maximum value and then declined slightly as the doping level was increased. The dependence of the specific electrical conductivity on dopant concentration can be well correlated with changes in morphology observed. The conductive polymer chains changed from assuming three dimensional random-coil structures to rod-like fabrillar structures. q 2000 Elsevier Science S.A. All rights reserved.