Electrochemically Prepared Polypyrroles from Aqueous Solutions
| Autor: | Renyuan Qian, Jinjin Qiu |
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| Rok vydání: | 1987 |
| Předmět: | |
| Zdroj: | Polymer Journal. 19:157-172 |
| ISSN: | 1349-0540 0032-3896 |
| DOI: | 10.1295/polymj.19.157 |
| Popis: | Polypyrrole (PPy) films generated electrochemically from aqueous solutions have been found to have also good electrical conductivity. PPy films with the counter anions TsO−, SO4=, and NO3− showed compact structure with apparent densities close to their flotation densities. The oxidative stability of PPy films has been compared by the value of the oxidation peak Epa around 1.0 V (vs. SCE) in the cyclovoltammogram. Prolonged electrolysis at +0.8 V led to oxidative degradation. The temperature dependence of the conductivity followed the variable range hopping equation. However voltage shorted compaction (VSC) conductivity measurements might show pronounced differences at low temperatures for some of these films. No significant frequency dependence of the conductivity was found up to 35 GHz. In the IR spectra of electrochemically reduced PPy film by transmission the v (N-H) and sp2 v (C-H) absorption bands were observed with no sp3 v (C-H) bands. On grinding the reduced film with KBr to make powder compact the sp3 v (C-H) absorption bands appeared indicating a mobile proton on the N-atom of the pyrrole ring. Definite evidence from IR spectra for the de-intercalation of the counter anion of the conducting PPy film during electrochemical reduction and chemical compensation has been obtained. The intercalation and de-intercalation of the counter anions was found to be accompanied by profound morphological changes. Molecular composites from in situ polymerization of aqueous pyrrole solution in a flexible polymer are briefly discussed. |
| Databáze: | OpenAIRE |
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