Graphite Electrodes Coated with Poly(dimethyldiallylammonium)chloride Network Films Cross-Linked by Gamma-Irradiation

Abstract

Properties of graphite electrodes coated with poly(dimethyldiallylammonium) chloride (PDMDAAC) are described. Gamma-irradiation was used to immobilize the polymer on the graphite surface by cross-linking the water-soluble polymer into an insoluble network. Immobilization of the network is aided by the high porosity of the graphite electrodes. Potassium ferricyanide was used as a model analyte to demonstrate electrochemical properties of the polymer modified electrode. Cyclic voltammograms of Fe(CN)63– at the PDMDAAC modified electrodes exhibit partitioning of the analyte into the polymer film. Chronocoulometry was used to determine the quantities of Fe(CN)63– trapped in the polymer network. The results of ion-exchange reactions of Fe(CN)63– with the PDMDAAC film were used to determine distribution coefficients (Kd) between the polymer film and the bulk solution of the analyte. Kd is 4000 for 0.01 M Fe(CN)63– in 0.2 M KCl. Analytical calibration plots of cyclic voltammetric peak currents for Fe(CN)63– at gamma-irradiated PDMDAAC/graphite electrodes were linear from 0.01 mM to 0.4 mM. Substantial enhancement of current signal was observed at the PDMDAAC modified graphite vs. bare electrodes. Variation in radiation dosage from 0.48 to 5.5 Mrad does not change the cross-link density of PDMDAAC on the graphite surface as evidenced by almost identical cyclic voltammograms of Fe(CN)63– at electrodes exposed to dosages over this range.