Detection of intermediate during the electrochemical polymerization of azure B and growth of poly(azure B) film

The electrochemical polymerization of azure B has been studied using the ro tating ring-disk electrode (RRDE) and the electrochemical quartz crystal mi crobalance (EQCM). The electrolytic solution consisted of 2.5 mmol dm(-3) a zure B, 0.2 mol dm(-3) NaH2PO4 and 0.5 mol dm(-3) NaCl with various pH valu es. An intermediate was generated at the disk electrode and was collected. The collection efficiency increases with decreasing ring potential as well as increasing rotation rate. Thus, the intermediate carries a positive char ge and is not too stable. Based on the determination of the frequency respo nse of the EQCM, the polymerization rate of azure B increases slowly before the fifteenth cycle, and then increases quickly with increasing number of potential cycles. The EQCM is a very useful tool for determination of the s tarting polymerization potential of azure B, which is 0.60 V (vs. SCE) in t his case. The maximum frequency difference during the oxidation and reducti on processes of poly(azure B) film in the solution with pH 3.0 is 174.7 Hz, which corresponds to a mass change of 0.99 mug cm(-2).