S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Chemical and Biological Engineering (화학생물공학부) Journal Papers (저널논문_화학생물공학부)
Electron transport dynamics in partially quaternized poly(4-vinylpyridine) thin films containing ferri/ferrocyanide
- Oh, Seung Mo; Faulkner, Larry R.
- Issue Date
- J. Electroanal. Chem, 269(1989) 17
- Electron transport dynamics were studied for the Fe(CN)z-*4- couple incorporated m partiallyquatemized
polyvinylpyridine (QPVP) modified electrodes. The goal was to identify the major factors
controlling electron diffusion in the electroactive polymer films. Variable-temperature (O-30 o C) chronocoulometry
was employed to measure the electron diffusion coefficients ( D,) and activation energies
(E, ) for the electron transport. The E, values were in the range of 24-80 kJ/mol (6-20 kcal/mol): E,
increased steadily as the concentration of the fern/ferrocyanide couple was Increased in the fdms; E,
was also influenced strongly by the anionic species (nitrate, p-toluenesulfonate, and perchlorate) in the
aqueous electrolyte adjacent to the film. The DE values in the presence of nitrate were compared to those
measured by a form of steady-state voltammetry. The electron diffusion coefficients were essentially
equal by both methods. The permeability of Fe(dmbpy),+ ion was measured m QPVP films loaded with
Fe(CN);-4- and exposed to nitrate; the observed permeation rates ( DS.&) were normally much larger
than the electron diffusion coefficients. The results suggest that counterlon motion is not a factor fimitmg
the electron motion. The polymer lattice clearly becomes more crosslinked upon taking up the redox ions,
an effect that induces a loss in short-range ion mobility within the film and causes a decline in .!I, as the
film 1s more heavily loaded. The anion dependence of E, was explained on the basis of changes in
internal structure reflecting interactions between the cationic polymer lattice. the anionic species in the
background electrolyte, and the solvent, Perchlorate produces nearly dehydrated, rather impermeable
films. The anion dependence is shown to be a structural, not a dynanuc. effect.
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