M. E. Jozefowicz

Polyaniline: Oriented Films and Fibers

Abstract The dependency of the conductivity of polyaniline (emeraldine oxidation state) on its molecular weight has been determined. Uni- and biaxially oriented films and uniaxially oriented fibers of emeraldine base have been studied and the dependency of their degree of crystallinity, tensile strength, and conductivity (after doping) on draw ratio has been determined.

X-ray structure of polyanilines

Abstract We describe two classes of the emeraldine form of polyaniline, Class I exhibits ES-I crystal structure in the HCl salt form and in the base form it is amorphous EB-I. Class II materials form partially crystalline structures EB-II and ES-II in base and HCl salt forms, respectively. We compare structural results on emeraldine with data for partially crystalline leucoemeraldine base (LEB) and pernigraniline base (PNB) — the fully reduced and oxidized forms of polyaniline, respectively. We contrast our studies of the EB-I/ES-I system with results for poly( o -toluidine) base, POT-EB and hydrochloride, POT-ES.

Structural aspects of the polyaniline family of electronic polymers

Abstract Recent structural studies of the polyaniline family of electronic polymers in its base and salt forms are reviewed, including a description of their crystalline and amorphous structures. Implications of some relevant structural parameters for the control of physical properties of these materials are also discussed.

Protonic acid doping of two classes of the emeraldine form of polyaniline

Abstract We compare the HCl doping data for the two recently discovered classes of polyaniline. The EB-II-ES-II system was found to be more difficult to dope in the pH range 2–3 than the previously studied EB-I-ES-I system. We discuss the influence of the crystallinity of the sample on its doping behavior.

Time dynamics of growth and decay of photoinduced defects in poluanilines

Abstract Polyanilines differ from other electronic polymers in the presence of very long-lived photoinduced absorptions, attributed to pinning of ring-rotational polarons of large effective mass. We report the growth and decay kinetics of long-lived photoinduced absorption in polyanilines. The intensity of the photoinduced 1130 cm −1 peak is monitored for periods of hours both with exciting laser light on and after it has been turned off. Photoinduced signal growth exhibits a stretched-exponential behavior in all oxidation states of polyaniline at low temperatures and does not saturate even after hours of irradiation. Photoinduced signal decay (after the pump light is turned off) is very slow, with half-life of the order of days. The evolution of the electronic photoinduced peak at 1.4 eV scales with that of vibrational peaks, indicating that the mass of photoinduced defects does not change with time. Several models that give rise to stretch-exponential kinetics are reviewed. Comparison with ligth-induced electron spin resonance studies suggests that serial growth and decay are the origins of the very large range of time dynamics in this system.