摘要
The combination of reflectance UV-Vis spec- troelectrochemistry with electrochemical quartz crystal microbalance (EQCM) and separate reflectance FTIR char- acterization were used to investigate the structural intercon- version for poly(o-phenylenediamine) (PoPD) between its ladder structure with phenazine units and polyaniline-like linear chains. The poly(o-phenylenediamine) films potentio- statically (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) aque- ous 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 po- tential cycling in 0.10 mol·L-1 aqueous H2SO4, the molar per- centage of the polyaniline-like chains was estimated to be 19% (relative to total phenylenediamine units), being in agreement with the result obtained from a formaldehyde- combination 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 com- pletely converted via intramolecular cyclization into the lad- der structure with phenazine units. However, PoPD1 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.
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, PoPD1 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.
基金
This work was supported by the National Natural Science Foundation of China(Grant Nos.20275010,20335020)
Hunan Province(Grant No.02JJY4054)
the Basic Research Special Program of the Ministry of Science and Technology of China(Grant No.2003CCC00700)
the Foundation of the Ministry of Education(MOE)of China(Grant Nos.jiaorensi[2000]26,jiaojisi[2000]65).
关键词
压电效应
光谱电子学
阶梯结构
聚乙烯
结构互换
piezoelectric spectroelectrochemistry, poly（o-phenylenediamine）, ladder structure with phenazine units, polyaniline-like chains, structural interconversion.
