Evolution of the conducting state of polyaniline from localized to mesoscopic metallic to intrinsic metallic regimes

J. Joo, E. J. Oh, G. Min, A. G. MacDiarmid, A. J. Epstein

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75 Citations (Scopus)


The results of microwave dielectric constant (ε{lunate}mw) and dc conductivity (σdc) of doped polyaniline (PAN) samples in different charge delocation regimes are reported. With camphor culfonic acid doped PAN prepared in m-cresol solvent (PAN-CSA (m-cresol)) respresenting the most delocalized material, a negative ε{lunate}mw is measured indicating an intrinsic metallic state. The Drude model at low frequency is used to estimate a relatively small plasma frequency ωp {reversed tilde equals} 0.015 eV and an anomalously long scattering time τ {reversed tilde equals} 1.2 × 10-11 s. This τ implies the importance of phonon back scattering for the most delocalized electrons as expected for the open Fermi surface of a highly anisotropic metal. Depending on the crystallinity, there are two different charge localization regimes in PAN samples: uncoupled metallic islands and coupled "mesoscopic" metallic state. The three-dimensional nature of metallic state is demonstrated by the correlation of low temperature dielectric response with the parallel and perpendicular crystalline domain lengths obtained from x-ray data. The charge localization to delocalization transition dependence on the polymer processing will be discussed. We present the temperature dependent nonmetal-metal transition for some preparations of PAN-CSA (m-cresol). The intrinsic conductivity of metallic PAN is estimated to be ∼ 107 S/cm.

Original languageEnglish
Pages (from-to)251-254
Number of pages4
JournalSynthetic Metals
Issue number1-3
Publication statusPublished - 1995 Mar 1
Externally publishedYes

Bibliographical note

Funding Information:
The authors acknowledge discussions with V. N. Prigodin and x-ray scattering experiments and discussions with J. P. Pouget. We thank ONR Grant No. N0001492-J1369 for financial support.

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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