Study on the kinetics of ferrocene derivatives in polymer electrolyte/electrode interface at microelectrode

Heterogeneous electron transfer rate constants (ks) and diffusion coefficients (D) of the ferrocene and its derivatives, in a new synthetic comb polymer solvent, poly(dimethylsiloxane-g-monomethylether polyethylene glycol) (SCP), and several other polymer solvents were estimated by using microelectrodes. Also, the influence of various supporting electrolytes on ks and D of ferrocene was studied. It was shown that ks and D of ferrocene decreased with increasing anionic size of the supporting electrolyte, but ks tended to increase with increasing radius of the solvated cation. Also, the cationic size of the supporting electrolytes had little effects on D. The values of ks and D for the ferrocene derivatives in the polymer solvents were in sharp contrast to those in monomeric solvents. Thus, the ks values were proportional to D in the polymer solvents, which indicates that solvent dynamics control of the electrode reaction. The values of ks and D of ferrocene in SCP were larger than those in other polymer solvents indicating that SCP is a good polymer solvent.