O. Hatozaki et Fc. Anson, DIFFUSION-COEFFICIENTS OF INTRINSICALLY ELECTROACTIVE POLYELECTROLYTES AND OF COUNTERIONS BOUND TO THEM, Journal of physical chemistry, 100(20), 1996, pp. 8448-8453
An electroactive label was attached to poly(acrylic acid) (molecular w
eight = 5000) by reaction with ferrocenylethanol. The resulting ferroc
ene label was stable when the polymer was dissolved in aqueous solutio
ns, and the diffusion coefficient of the labeled polymer was estimated
from the currents obtained as the ferrocene was oxidized at a rotatin
g disk electrode. Although strong adsorption of the polymer on the ele
ctrode surfaces depressed the oxidation currents below the convection-
diffusion controlled values at rotating disk electrodes, it was still
possible to estimate diffusion coefficients by appropriate analysis of
the rotation rate dependences of the measured currents. At pH values
where the labeled polymer became a polyanion, its diffusion coefficien
t was also estimated from the reduction currents for Ru(NH3)(6)(3+) or
Co(NH3)(6)(3+) counterions bound electrostatically to the polyelectro
lyte. Good agreement was obtained between the diffusion coefficients e
stimated by the two independent routes.