Co. Dasenbrock et al., EVALUATION OF THE ELECTROCHEMICAL CHARACTERISTICS OF A POLY(VINYL ALCOHOL) POLY(ACRYLIC ACID) POLYMER BLEND, Electrochimica acta, 43(23), 1998, pp. 3497-3502
The polymer blend poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) has
been evaluated as a coating on graphite electrodes. The uptake of tri
s(2,2'-bipyridyl)ruthenium(II), Ru(bpy)(3)(2+), by the film was monito
red by cyclic voltammetry and was found to be pH dependent. A plot of
current response versus pH is analogous to a titration curve of a mixt
ure of acids with pK(a) values in the range of 4-6. At pH 1 where the
PVA/PAA film is neutral, voltammograms of Ru(bpy)(3)(2+) were comparab
le to ones recorded at a bare electrode. At pH 7, where the film is an
ionic because the carboxyl group is deprotonated, a current enhancemen
t factor of 9 to 16 compared to a bare electrode was obtained. This pH
-dependent behavior is also observable for plots of the peak separatio
n versus pH in which E-p of cyclic voltammograms increases with pH. Th
e effect of different supporting electrolytes was investigated by meas
uring the current response with LiNO3, NaNO3, and KNO3 over a range of
pH. Cyclic voltammograms of Fe(CN)(6)(3-) showed that negatively char
ged species are rejected by the polymer film. (C) 1988 Elsevier Scienc
e Ltd. All rights reserved.