EFFECTS OF ADSORPTION AND ASSOCIATION WITH MULTIPLY-CHARGED COUNTERIONS ON THE ELECTROCHEMICAL RESPONSES OF AN ELECTROACTIVE POLYELECTROLYTE

The preparation of two copolymers of vinylferrocene and 4-(vinylpyridi ne) containing a few per cent of ferrocene groups and having molar mas ses of 2.3 X 10(5) and 2.4 X 10(4) gmol(-1) is described. The copolyme rs were dissolved in aqueous hydrochloric acid, where their electro-ox idation was examined by voltammetry at rotating disk electrodes, Sever e adsorption on the electrode surface of the higher molar mass copolym er interfered with the evaluation of its diffusion coefficient, but va lues were obtained for the lower molar mass copolymer. The effects of pH, ionic strength and electrostatic binding of multiply charged count erions on the diffusion of both copolymers were examined. The uncertai nties inherent in the use of electrochemical methods to evaluate appar ent diffusion coefficients of polymers in mixtures with varying molar masses are pointed out.