Electronic Phenomena in Polyanilines
Technical rept. 31 May 1991-30 Jun 1992,
PENNSYLVANIA UNIV PHILADELPHIA DEPT OF CHEMISTRY
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Polyanilines have been known for over one hundred years. Recent studies of this chemically flexible polymer have demonstrated unusual chemical, electrical, and optical phenomena, both in insulating forms and conducting forms. Polyaniline has three stable insulating forms, leucoemeraldine base LEB, emeraldine base EB, and pernigraniline base PNB. These three forms exhibit differing phenomena ranging from intramonomer luminescing excitons and ring rotation polarons in LEB, to nonluminescing charge transfer excitons and also ring rotational polarons in EB, to a degenerate ground state with bond order parameter solitons and ring order parameter polarons in PNB. The LEB form can be p-doped oxidatively doped, the EB form can be protonic acid doped and the PNB form can be n-doped reductively doped to form conducting systems. Charge conduction studies of oriented films and fibers demonstrate that three- dimensional order between chains is critical for high conductivities. The ability to derivatize polyaniline at ring and nitrogen positions allows one to test concepts for the control of conductivity as well as improved processing.
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