Synthesis of polypyrrole

Thiophene and its derivatives can undergo both chemical and electrochemical oxidation to produce PTs [12,13]. The electrochemical synthesis of PTis more difficult as the oxidation potential of thiophene monomer is relatively high compared to that of other monomers such as pyrrole or aniline. Thus, strong oxidants are required for the polymerization of thiophene. The reaction mechanism is similar to PPy synthesis. 

Caution Carry out all procedures in a well-ventilated fume-cupboard, wear appropriate disposable gloves, a lab-coat, and safety glasses. 

Preparation pyrrole is distilled slowly from calcium hydride under reduced pressure prior to use and stored in the fridge in a brown bottle at 4 °C. 

The solution is poured into the electrochemical cell. This cell is flat bottomed and cylindrical in construction and has a gas inlet and two side-arms with female Quickfit joints into which are inserted two male joints terminated with sintered-glass frits. The conducting-glass electrode is then attached to a crocodile clip with a long wire contact, which is clipped so that the crocodile clip is above the surface of the liquid. The graphite rod and SCE are then placed in the side-arms provided (separated from the solution by a sintered-glass frit). 

With the potentiostat on standby the electrodes are connected up to the correct outputs and the programme selected, for example, a potential of -P 1.0 V (versus SCE) is appropriate. 

The potentiostat is switched on and a black film is seen to form on the electrode. Electrolysis is then continued for about 30 mins. The black film is then washed and peeled from the electrode for subsequent analysis. 

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The early history of the DCC field is coincident with the publication of a series of landmark papers from the Dervan laboratory, describing a code for the design and synthesis of polypyrrole-polyimidazole compounds... 

Comparable to thiophene, pyrrole is a five-membered heterocycle, yet the ring nitrogen results in a molecule with distinctly different behavior and a far greater tendency to polymerize oxidatively. The first report of the synthesis of polypyrrole (PPy) 62 that alluded to its electrically conductive nature was published in 1968 [263]. This early material was obtained via electrochemical polymerization and was carried out in 0.1 N sulfuric acid to produce a black film. Since then, a number of improvements, which have resulted from in-depth solvent and electrolyte studies, have made the electrochemical synthesis of PPy the most widely employed method [264-266]. The properties of electrosynthesized PPy are quite sensitive to the electrochemical environment in which it is obtained. The use of various electrolytes yield materials with pronounced differences in conductivity, film morphology, and overall performance [267-270]. Furthermore, the water solubility of pyrrole allows aqueous electrochemistry [271], which is of prime importance for biological applications [272]. 

Chen, J.H., Huang, Z.P., Wang, D.Z., et al. (2001). Electrochemical synthesis of polypyrrole/carbon nanotube nanoscale composites using weU-aligned carbon nanotube arrays. Appl. Phys. A Mater. Sci. Process, 73, 129-31. 

The chemical synthesis of Polypyrrole-themio-plastic powder blend [127]. 

The vapour phase synthesis of polypyrrole in order to form a gradient of conductivity in a porous substrate (foam, honeycomb) [168]. 

The first synthesis of polypyrrole, appreciating its conducting properties, was described in 1968 [80]. Electrochemical oxidation of a pyrrole solution in 0.1 N sulfuric acid afforded a black conducting film. Improvements through the use of organic solvents and different electrolytes have been made [81, 82] and the electrochemical method has been the most employed polymerization technique ever since. Oxidized polypyrrole is stable under ambient conditions and up to temperatures exceeding 300 °C [82]. The neutral form of polypyrrole, on the other hand, has not been isolated... 

Exercise 3.11. As an exercise in a chemometrics course, M.R. Vallim and V.F. Juliano analyzed data obtained by a research worker in a series of experiments involving the synthesis of polypyrrole in an EPDM matrix. Three factors were studied reaction time (t), oxidant concentration (C) and particle size (P). The response observed was the reaction yield. Using the data presented below, calculate the values of the effects and their standard errors. Before doing this, however, carefully examine the set of response values, taking into account the signs of the design matrix. Is it possible to anticipate which variable has the largest influence on the yield ... 

Parameters used in the simultaneous optimization of the responses of the synthesis of polypyrrole in EPDM rubber. The values in parentheses are the desirabilities of the corresponding response levels... 

J. Duchet, R. Legras, and S. Demoustier-champagne, Chemical synthesis of polypyrrole stmeture-properties relationship, Synth. Met., 98, 113 122 (1998). 

A. Eftekhari, M. Harati, and M. Pazouki, Electrocbemical synthesis of polypyrrole macro-tubes on aluminum substrate, Synth. Met., 156(9-10), 643-647 (2006). 

M. Bazzaoui, J.I. Martins, S.C. Costa, E.A. Bazzaoui, T.C. Reis, and L. Martins, Sweet aqueous solution for electrochemical synthesis of polypyrrole Part 2. On ferrous metals, Electrochim. Acta, 51,4516-4527 (2006). 

In order to immobilize enzymes in conducting polymers to fabricate biosensors, the electrochemical synthesis of polypyrrole films was studied under different conditions. It was found that the size and morphology of polypyrrole films synthesized using cyclic voltammetry were affected by the concentration of the supporting electrolyte at a scan potential range between 0.0 and 1.0 V (vs. SCE), and at a scan rate of 48 mV s [47]. The diameters of particles prepared in a solution containing 0.10 M pyrrole and 0.10 M NaCl... 

The fabrication of polypyrrole wires via electropolymerization within poly(methyl methacrylate) nanochannels on an indium tin oxide (ITO) substrate was reported by Chen et al. [53]. The electrochemical synthesis of polypyrrole was performed by a cyclic voltammetry method in aqueous 0.1 M NaC104 containing 0.1 M pyrrole monomer. The potential was scanned 10 times between -0.7 and +0.6 V vs. Pt at a scan rate of 100 mV s . The nanochannels act as templates for electropolymerization of polypyrrole nanowires. 

The synthesis of polypyrrole-heparin nanotubes was performed at a constant potential of 0.8 V (vs. SCE), using a nanoporous membrane as a template [71]. Heparin, which is a bioactive polyelectrolyte, was used as the doping anion. The use of a bioactive doping compound, which provides interesting biological properties in the composite sample, allows the fabrication of functionalized surfaces able to promote direct electronic communication between biological species and substrates. This result also confirmed that the... 

J.M. Chen, S.W. Liao, and Y.C. Tsai, Electrochemical synthesis of polypyrrole within PMMA nanochannels produced by AFM mechanical lithography, Synth. Met., 155, 11-17 (2005). 

Synthesis of polypyrrole nanoparticles was achieved using micro-emulsion polymerization system by oxidation of pyrrole monomer with FeCl3.6H20. As the oxidant was added, the color of the solution changed from colorless to deep greenish black which is an indication of oxidation of conducting polypyrrole. The reaction product polypyrrole was obtained in the form of black powder. 

Lin, E.-R, Chiu, C.-J., and Tsai, Y.-C. [2014]. One-step electrochemical synthesis of polypyrrole-graphene-glucose oxidase nanobiocomposite for glucose sensing, J. Electrochem. Soa, 161, pp. B243-B247. 

Synthesis of Polypyrrole and PEDOT Carbon Nanofiber Composites... 

Yoneyama H., Shoji Y, and Kawai K., Electrochemical synthesis of polypyrrole films containing metal oxide particles, Chem. Lett, 1989, 1067-1070. 

Shi W., Liang P, Ge D., Wang J. and Zhang Q. (2007). Starch-assisted synthesis of polypyrrole nanowires by a simple electrochemical approach. Chemical Communications, (23), 2414-2416. 

FIGURE 8.9 Schematic representation of the synthesis of polypyrrole-coated polystyrene latexes using a physically adsorbed poly(N-vinylpyrrolidone) stabilizer. (From Lascelles, S.F., and Armes, S.R, /. Mater. Chem., 7, 1339, 1997. With permission.)... 

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