Composites of polypyrrole and carbon black: Part III. Chemical synthesis and characterization

Wampler, Wesley; Rajeshwar, Krishnan; Pethe, R.G.; Hyer, R. C.; Sharma, S. C.

doi:10.1557/jmr.1995.1811

Cited by 38 publications

(16 citation statements)

References 38 publications

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“…9 A new PS reagent for the synthesis of blactams in solution was studied by Donati et al 10 Recently, it has been shown that conducting polymer films can be used to reduce Cr(VI). Rajeshwar and coworkers [11][12][13] observed the reduction of hexavalent chromium at a polypyrrole electrode with 100% efficiency. The reversibility of the polymer redox process enabled the electrochemical recycling of the polypyrrole for repeated treatment of Cr(VI).…”

Section: Introductionmentioning

confidence: 99%

Synthesis of a cellulose‐grafted polymeric support and its application in the reductions of some carbonyl compounds

Dhiman

Kaur

Mahajan

2007

J of Applied Polymer Sci

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The reduction of carbonyl compounds by borohydride supported on a cellulose-anion exchange resin is known. The synthesis of a graft copolymer of cellulose and poly(4-vinyl pyridine) [CellO-g-poly(4-VP)] has been carried out with ceric ions as a redox initiator. A postgrafting treatment of CellO-g-poly(4-VP) with sodium borohydride has produced CellO-g-poly(4-VP) borane, a polymer-supported reducing agent. Optimum conditions pertaining to the maximum percentage of grafting have been evaluated as a function of the concentrations of the initiator, monomer, and nitric acid, amount of water, time, and temperature. The maximum percentage of grafting (585%) has been obtained with 0.927 mol/L of 4-vinyl pyridine and 0.018 mol/L of ceric ammonium nitrate in 120 min at 458C. The polymeric support, CellO-g-poly (4-VP) borane, has been used for reduction reactions of different carbonyl compounds such as benzaldehyde, cyclohexanone, crotonaldehyde, acetone, and furfural. The graft copolymer has been characterized with IR and thermogravimetric analysis. The grafted cellulose has been found to be thermally stable. The reduced products have been characterized with IR and NMR spectral methods. The reagent has been reused for the reduction of a fresh carbonyl compound, and it has been observed that the polymeric reagent reduces the compounds successfully but with a little lower product yield.

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Section: Introductionmentioning

confidence: 99%

Synthesis of a cellulose‐grafted polymeric support and its application in the reductions of some carbonyl compounds

Dhiman

Kaur

Mahajan

2007

J of Applied Polymer Sci

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“…More recently, it has been shown that conducting polypyrrole films can be used to reduce Cr(VI), opening up the possibility of a new remediation-control technology [7][8][9][10][11][12]. Polypyrrole (PPy) is a well-known conducting polymer and can undergo good reversibility between its conducting and insulating states.…”

Section: Introductionmentioning

confidence: 99%

“…Polypyrrole (PPy) is a well-known conducting polymer and can undergo good reversibility between its conducting and insulating states. During reduction, anionic sites are formed that require cations for charge compensation (or anion expulsion) while upon oxidation, cationic sites such as polarons (PPy The first report of the reduction of hexavalent chromium at a conducting polymer matrix was made in 1993 by Rajeshwar and co-workers [7][8][9] who observed the reduction of hexavalent chromium at a polypyrrole electrode, with approximately 100% efficiency, and at time intervals spanning only minutes. Furthermore, the reversibility of the polymer redox process enabled the electrochemical recycling of the polypyrrole for repeated treatment of Cr(VI).…”

Section: Introductionmentioning

confidence: 99%

Reduction of hexavalent chromium at a polypyrrole-coated aluminium electrode: Synergistic interactions

Conroy

Breslin

2004

Journal of Applied Electrochemistry

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Adherent polypyrrole films were electropolymerized from a tosylic acid solution onto an aluminium substrate and used for the reduction of Cr(VI). The reduction of Cr(VI) to the trivalent state was found to proceed by pseudofirst-order kinetics with an activation energy barrier of 15.13 kJ mol )1 . This catalyst could be regenerated by reducing the composite at a sufficiently negative potential, in the absence of Cr(VI). However, it was found that the catalyst functioned also through a self-sustained regeneration mechanism. In this mechanism, Cr(VI) was reduced by PPy 0 to generate PPy þ , but the PPy þ was subsequently reduced to PPy 0 by oxidation of the aluminium substrate, thus regeneration of the catalytic PPy 0 surface giving rise to a synergistic action between the polypyrrole and the aluminium substrate.

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“…These classes of composites could be obtained by the in situ deposition of the ICP on CB substrate [18,22] , the direct polymerization of ICPs on carbon substrates, by chemical [23,21,24] or electrochemical method [25][26][27][28] . The chemical process yields to large quantities of ICPs [29] .…”

Section: Introductionmentioning

confidence: 99%

“…Composites obtained by deposition of ICPs over CB particles, showed thermal stability and effective reduction of the surface area and pore volume of the CB [18,21] . These classes of composites could be obtained by the in situ deposition of the ICP on CB substrate [18,22] , the direct polymerization of ICPs on carbon substrates, by chemical [23,21,24] or electrochemical method [25][26][27][28] .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of conducting composites of polyaniline and carbon black with high thermal stability

2009

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nanotubes substrates have demonstrated some properties such as the increase of the PANI conducting ability [27,32,33] , the supercapacitive behavior [30,34] as well as better recovering properties by functionalizing the oxidized carbon nanotube with p-phenylenediamineamino before starting the polymerization [35] . Nevertheless, the attainment of a well controlled carbon nanotube substrate, with high purity degree, is still difficult and expensive.In this work, a detailed and simple route is described to prepare composites based on the direct chemical polymerization of PANI onto particles of conductive CB substrate (type Printex ® L6 from Degussa S.A). It is also demonstrated that this procedure presents great advantages such as the best control in the substrate recovering. The composites were characterized by thermal analysis, specific area, elemental analysis and AC conductivity. ExperimentalAniline (Aldrich) was purified by distillation under reduced pressure in the presence of zinc powder. Conductive CB Printex ® L6 (10 -1 S cm -1 in pressed samples) was purchased from Degussa. All reagents were analytical grade and used as received. The water used for the solutions was purified by the Milli-Q system (Millipore Inc.).The PANI was synthesized using aqueous HCl by the direct oxidation of the aniline with the addition of a solution of 0.25 M (NH 4 ) 2 S 2 O 8 using a monomer:oxidant molar ratio of 4:1 at 0 °C. The resulting PANI powder was dried under air atmosphere at 60 °C.The composites were prepared by maintaining CB under mechanical stirring for 1 hour in contact with acidic aqueous solutions of 1.0 M aniline in 1.0 M HCl. After that, the solution of 0.25 M (NH 4 ) 2 S 2 O 8 in 1.0 M HCl was drop wise IntroductionPANI presents very poor mechanical stability in its conducting state, which requires the preparation of copolymers or blends. Moreover, the polymer must be stable at the high temperatures that are necessary for processing [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . However, films prepared with intrinsically conducting polymers (ICPs) exhibit poor mechanical properties and are also thermally unstable [17,18] , for example, conducting PANI loses its electrical properties at 225 °C, even under nitrogen atmosphere.Generally, thermoplastics or thermosets conductive compounds are obtained by the addition of a conductive loading, such as CB, to the polymeric matrix. Additionally, to obtain suitable materials, high loadings of the additive are necessary. This makes heat processing difficult, because the high surface area additive increases the melt viscosity in the interaction with the polymer matrix [19,20] .Composites obtained by deposition of ICPs over CB particles, showed thermal stability and effective reduction of the surface area and pore volume of the CB [18,21] . These classes of composites could be obtained by the in situ deposition of the ICP on CB substrate [18,22] , the direct polymerization of ICPs on carbon substrates, by chemical [23,21,24] or electrochemical method [25][26][2...

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Composites of polypyrrole and carbon black: Part III. Chemical synthesis and characterization

Cited by 38 publications

References 38 publications

Synthesis of a cellulose‐grafted polymeric support and its application in the reductions of some carbonyl compounds

Synthesis of a cellulose‐grafted polymeric support and its application in the reductions of some carbonyl compounds

Reduction of hexavalent chromium at a polypyrrole-coated aluminium electrode: Synergistic interactions

Synthesis and characterization of conducting composites of polyaniline and carbon black with high thermal stability

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