Synthesis of polycatechol with electrochemical activity and its properties

The electrochemical polymerization of catechol on platinum has been carried out using repeated potential cycling between -0.2 and 1.1 V (versus SCE). The electrolytic solution consisted of 0.2 mol dm - 3 catechol, 0.5 moldm - 3 NaCI and 0.1 mol dm - 3 Na 2 HPO 4 with pH 8.72. Catechol can not be polymerized at pH > 10.12. Polycatechol has an electrochemical activity at pH ≤ 4. The anodic and cathodic peak potentials of polycatechol shift towards more negative values as the pH of the solution increases from 1 to 4. The electrochemical activity of polycatechol hardly changes in this pH region, but it decreases slowly with time. This is caused by oxygen in air, which leads to an irreversible oxidation of polycatechol. This property is favorable for protecting metals from corrosion. Raman and FTIR spectra of polycatechol and catechol are quite different. AFM images of polycatechol films provide evidence that the image of the oxidized state of polycatechol is markedly different from that of the reduced one. This difference is caused by doping and dedoping of polycatechol.