Polyanilines: From solitons to polymer metal, from chemical currosity to technology

Polyanilines are particularly flexible family of electronic polymers. There are three insulating forms; one of which, pernigraniline base, sustains soliton excitations with very unusual properties due to the key role of ring-torsion angle alternation in additon to bond length dimerization. Protonation of the emeraldine base form leads to the conducting emeraldine salt. The conducting state of the material is very sensitive to the degree of local order. A Drude metallic response is observed for the most coducting of these materials, though the dc through optical conductivity are dominated by inhomogeneous disorder. Potential applications in the areas of electromagnetic interference elimination and joining of plastics are described.