A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Polyaniline Versus Polyacetylene, or, Rings Versus Bonds and the Roles of Barriers and Crystallinity
Abstract Wide-spread study of polyacetylene for the past decade has demonstrated that the energy gap of trans-polyacetylene is due to the electron-phonon interaction with some contribution from the Coulomb interaction. Injected charge carriers in soliton and polaron states have modest masses, of order me. The time dynamics for the relaxation of photoinduced charge indicate that there are no very long-lived states. The leucoemeraldine and emeraldine forms of polyaniline differs substantially from polyacetylene. Their large energy gaps have origin in the electronic structure of C6 rings. Additional injected charges form very long-lived polaron states, the masses of which are 50–100 me. The dramatic difference in the behavior of polyaniline with respect to polyacetylene reflects the important role of ring-torsion angles. Highly doped New-polyacetylene has conductivity o in excess of 104 S/cm. Combined conductivity, thermopower, susceptibility and magneto-resistance studies show that the charge motion is three-dimensional and barrier limited. In contrast, heavily doped polyaniline (emeraldine salt) has conductivities up to 102 S/cm. Extensive transport studies show that though the charge motion is three-dimensional, the “metallic” regions are sufficiently small such that charging energy limited tunneling dominates the measured resistance. The ability to derivatize the polyaniline system enables the control of the separation between the polyaniline chains. Systematic study of this has shown the important role of localization of charge as the chains are separated. Recent advances in synthesis and processing of polyaniline including oriented films, fibers, and even a self-doped derivative have opened up new opportunities for basic studies and applications.
Polyaniline Versus Polyacetylene, or, Rings Versus Bonds and the Roles of Barriers and Crystallinity
Abstract Wide-spread study of polyacetylene for the past decade has demonstrated that the energy gap of trans-polyacetylene is due to the electron-phonon interaction with some contribution from the Coulomb interaction. Injected charge carriers in soliton and polaron states have modest masses, of order me. The time dynamics for the relaxation of photoinduced charge indicate that there are no very long-lived states. The leucoemeraldine and emeraldine forms of polyaniline differs substantially from polyacetylene. Their large energy gaps have origin in the electronic structure of C6 rings. Additional injected charges form very long-lived polaron states, the masses of which are 50–100 me. The dramatic difference in the behavior of polyaniline with respect to polyacetylene reflects the important role of ring-torsion angles. Highly doped New-polyacetylene has conductivity o in excess of 104 S/cm. Combined conductivity, thermopower, susceptibility and magneto-resistance studies show that the charge motion is three-dimensional and barrier limited. In contrast, heavily doped polyaniline (emeraldine salt) has conductivities up to 102 S/cm. Extensive transport studies show that though the charge motion is three-dimensional, the “metallic” regions are sufficiently small such that charging energy limited tunneling dominates the measured resistance. The ability to derivatize the polyaniline system enables the control of the separation between the polyaniline chains. Systematic study of this has shown the important role of localization of charge as the chains are separated. Recent advances in synthesis and processing of polyaniline including oriented films, fibers, and even a self-doped derivative have opened up new opportunities for basic studies and applications.
Polyaniline Versus Polyacetylene, or, Rings Versus Bonds and the Roles of Barriers and Crystallinity
Epstein, A. J. (author) / MacDiarmid, A. G. (author)
1990-01-01
11 pages
Article/Chapter (Book)
Electronic Resource
English
Conductivity and thermopower of doped polyacetylene and polyaniline
| British Library Online Contents | 1993
New Developments in the Synthesis and Doping of Polyacetylene and Polyaniline
| Springer Verlag | 1990
Clash points; Cash retentions versus bonds
British Library Online Contents
Clash point - Cash retentions versus bonds
Online Contents | 1998
Properties of Metal-Polyaniline Schottky Barriers
| British Library Online Contents | 1999