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Ion exchange, anisotropic structure and thermal stability of polypyrrole films

journal contribution
posted on 01.03.1995, 00:00 authored by V T Truong, B Ennis, Maria ForsythMaria Forsyth
The thermal stability of electrochemically prepared polypyrrole (PPy) films with p-toluene sulfonate (pTS) or perchlorate (CIOP4) counter ion (PPy/pTS and PPy/ClO4) is improved by simple treatment with aqueous sulfuric acid, sodium sulfate or sodium bisulfate. The degree of stabilization achieved depends on the solution, temperature and duration of treatment. PPy/pTS is easily stabilized and thick films (43μm) retain 90 % of the initial conductivity after long period (300 h) at 150 °C, while thinner films (12 μm) retain slightly less (70 %). A model for the conductivity decay has been proposed. Although the mechanism for improved stability is not yet clear it is apparent that the level of ion exchange and the original polymer microstructure are important. The early stages of ion exchange are not symmetrical and diffusion is facilitated at the electrode side of the film. Furthermore, X-ray diffraction shows no evidence of morphological change after treatment of thick PPy/pTS but in thin PPy/pTS and PPy/ClO4 films an additional peak is indicative of more ordered structure following treatment. These observation may imply that there is a higher density of crosslinks and branching at the growth side than at the electrode side of the film.

History

Journal

Synthetic metals

Volume

69

Issue

1-3

Pagination

479 - 480

Publisher

Elsevier S.A.

Location

Basel, Switzerland

ISSN

0379-6779

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

1995, Elsevier Science S.A.