Electrochemical evaluation of charge-transport rates in polypyrrole

Abstract

using tq = 1.09 X 10"10 s obtained above. The best fit of to eq 3 is shown in Figure 2. It gives C = 1.047 and A -7.78.Considering the excellent linear correlation between and / , one can conclude that the pair correlation factor g2/J2, given in eq 1, is independent of temperature over the temperature range of-12 to 129.5 °C. Although dynamic pair correlation is known to be mostly negligible so that the parameter J2 is known to be mostly close to l,1 11the temperature-independence result for g2 does not suggest the presence of a mesomorphic transition in this system, because, as mentioned above, the presence of a mesomorphic transition will result in a change in the static pair correlation factor g2, resulting in a significant change in . Furthermore, the factor a in eq 2 (or A in eq 3) is related to the volume of the reorienting unit. The smoothness in the Debye-Stokes-Einstein plot, as shown in Figure 2, indicates no volume change in the -12 to 129.5 °C temperature range. Thus, corroborating the finding of polarized scattering,2 the depolarized Rayleigh scattering result clearly does not support the mesomorphic transition in the liquid phase in DOS or in the «-alkane system.Acknowledgment. We thank Professor E. W. Fischer for discussion. Acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial financial support of the research. Partial financial support by NSF (the polymer program, DMR-8606884) is also acknowledged.

Inorganic and biological electron transfer across an electronically conductive composite polymer membrane

“…Therefore, electron and ion transfer is not associated with oxidation of the undoped polymer as would be the case in an electrochemical experiment involving a polypyrrole film-coated electrode (2). In the electrochemical case, electrons and ions will flow across the polypyrrole film only until the polypyrrole is fully oxidized.…”

Mechanical performance of PPy helix tube microactuator

“…The actuation strain was considered proportional to charge transferred and independent of mechanical strain. [7][8][9] . On the other hand, a viscoelastic lumped parameter method was developed to describe the mechanical behaviour of CP actuators [10,11] and the model performance was verified both experimentally and using the complicated continuum mechanics method [11][12][13] based on Biot's poroelastic theory [14,15] .…”

A Simple Chemical Procedure for Extending the Conductive State of Polypyrrole to More Negative Potentials

“…Electronically conductive polymers can be electrochemically switched between electronically insulating and electronically conductive states [1][2][3][4][5]. This insulator/conductor conversion process is essential to many of the proposed applications of these polymers [5].…”

“…However, the conductor-to-insulator transition means that in a certain potential window, these polymers are electronic insulators [1][2][3][4]. This is a potential drawback in applications where electronic conductivity is required.…”

“…Because polypyrrole is an electronic insulator at potentials negative of ca. -0.4 V (vs. the saturated calomel electrode (SCE) in acetonitrile) [1][2][3][4], the film could not be used as an electrode for redox couples with E's negative of this potential [4].…”