Antioxidative Dopant for Thermal-Resisting Polypyrrole and Its Mechanism

Shinji Takeoka, Tomitaro Hara, Kazuaki Fukushima, Kimihisa Yamamoto, Eishun Tsuchida

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11 Citations (Scopus)


In order to improve the thermal stability of the electric conductivity of polypyrrole (PPy), a series of aromatic sulfonate derivatives having acid-type substitute groups, such as -COOH, -OH, and -SO3H, were used as dopants. The PPy doped with these dopants showed excellent thermal stability of their electric conductivity, even at 150 °C in air. Especially, 2-hydroxy-5-sulfobenzoic acid, having one -COOH and one -OH, provided the highest thermal stability; the doped PPy maintained 95% of its initial conductivity, even after heating for 8 h at 150 °C in air. Furthermore, the PPy showed 20-times higher stability against long-term heating at 125 °C for 1000 h in comparison with PPy doped with p-methylbenzenesulfonic acid, which is conventionally used to provide high thermal stability. The thermal-stabilization mechanism has suggested that dopants having acidic substituents should suppress proton dissociation from the N-position of the PPy main chain and keep the π-conjugation structure by supplying a proton from the acidic groups. Such a proton supplement was confirmed by the IR spectroscopy of deuterized PPy.

Original languageEnglish
Pages (from-to)1471-1476
Number of pages6
JournalBulletin of the Chemical Society of Japan
Issue number6
Publication statusPublished - 1998 Jun

ASJC Scopus subject areas

  • Chemistry(all)


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