Ring-Torsional Polarons in Polyaniline and Polyparaphenylene Sulfide
PENNSYLVANIA UNIV PHILADELPHIA DEPT OF CHEMISTRY
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The role of the dihedral angle of the backbone phenyl rings in determining the electronic structure and charge storage mechanism in polyaniline PAN and polyparaphenylene sulfide PPS is reviewed. The sensitivity of the average ring torsion angle to the effects of steric repulsion and electron delocalization is manifest in the effects of derivatization and temperature on the optical spectra of these materials. It is shown that charge is self-trapped into localized defect states in part via changes in ring angle, leading to novel ring-torsional polarons which induce only one defect level into the energy gap and possess a very large kinetic mass 50 - 500 me. Evidence for the existence of these defects in PAN and PPS is discussed.
- Polymer Chemistry