Zhang Youyu

Growth and Properties of Poly-o-aminophenol Films with Three Dimensional Combinations of in situ Electrochemical Quartz Crystal Microbalance and Fourier Transform Infrared Spectroelectrochemistry

Abstract A three-dimensional combined technique, in situ quartz crystal microbalance in combination with infrared spectroscopy and electrochemistry was proposed. With this combining technique, the depositing process of poly- o -aminophenol on gold electrode surface was monitored. The oxidation and polymerization of the o -aminophenol, as well as the electrochemical properties of poly- o -aminophenol in acidic solution were investigated. Information about mass coverage of polymer, the doping/dedoping process, and change in structure of the polymer were obtained simultaneously and discussed. The results indicated that this method could be widely applied to the investigation of electrode-surface-relevant processes.

A piezoelectric spectro-electrochemical study on the structural interconversion for poly(o-phenylenediamine) between its ladder structure with phenazine units and polyaniline-like chains

The combination of reflectance UV-Vis spectroelectrochemistry with electrochemical quartz crystal microbalance (EQCM) and separate reflectance FTIR characterization were used to investigate the structural interconversion for poly(o-phenylenediamine) (PoPD) between its ladder structure with phenazine units and polyaniline-like linear chains. The poly(o-phenylenediamine) films potentiostatically (0.8 V vs. SCE) grew on Au electrodes from 0.20 mol.L-1 H2SO4 (PoPD1) or 0.40 mol.L-1 NaOH (PoPD2) aqueous solution containing 0.20 mol.L-1 Na2SO4 + 0.10 mol.L-1 o-phenylenediamine. By considering the mass of deposited PoPD2 film obtained from the EQCM data and the charge consumed under the current peak at ca. 0.6 V vs. SCE for oxidation of -NH2 groups in as-prepared PoPD2 during potential cycling in 0.10 mol.L-1 aqueous H2SO4, the molar percentage of the polyaniline-like chains was estimated to be 19% (relative to total phenylenediamine units), being in agreement with the result obtained from a formaldehydecombination experiment through the aminocarbonyl reaction. After 40-cycle potential sweeps between 0.2 and 0.8 V vs. SCE the polyaniline-like chains in PoPD2 could be completely converted via intramolecular cyclization into the ladder structure with phenazine units. However, PoPü1 was found to be perfectly composed of the ladder structure with phenazine units, and after 40-cycle potential sweeps between-0.4 and 0.1 V vs. SCE only 2.5% in molar percentage of PoPD’s ladder structure could be converted into polyani line-like chains, suggesting that the ladder structure with phenazine units is thermodynamically more stable due to its possessing higher conjugation.