聚乙撑二氧噻吩阳极降解的研究

研究了聚乙撑二氧噻吩(PEDOT)膜在水溶液中的阳极降解过程. 研究发现PEDOT的阳极过程可以分为p掺杂区[电位范围－0.3～0.5 V (相对于饱和甘汞电极; vs. SCE)]、过渡区[电位范围0.6～1 V (vs. SCE)]、过氧化区[电位范围1.2～1.6 V (vs. SCE)]三个电位区域. 用电化学阻抗谱法、循环伏安法、红外光谱技术、膜电阻测量以及电子自旋共振技术分别研究了PEDOT膜在这三个电位区域的行为. 结果表明: PEDOT膜在这三个电位区域的性质有明显不同. 在p掺杂区PEDOT膜的官能团、共轭结构、导电性均保持, 即在这个电位区发生可逆的掺杂/脱掺杂反应, 膜几乎不降解. 在过渡区和过氧化区, PEDOT膜均发生了降解. 与传统的导电聚合物在高电位的阳极降解的过氧化过程不同, 我们认为膜在较高电位(过渡区)发生一个驰豫过程, 该过程使得膜的官能团改变, 但是膜的共轭结构和导电性均保持; 而在更高的电位区(过氧化区)膜的降解和一般意义的过氧化降解相同, 此时膜的官能团、共轭结构、导电性均发生不可逆的破坏.

Degradation of Poly(3,4-ethylenedioxythiophene) at an Anode

The degradation of poly(3,4-ethylenedioxythiophene) (PEDOT) films at an anode in an aqueous solution has been systemically studied. On the basis of results, the anodic processes can be divided into three segments: p-doping region from -0.3 to 0.5 V, transitional region from 0.6 to 1 V and overoxidative region from 1.2 to 1.6 V (all vs. SCE). The behaviors of PEDOT in the three potential regions were studied by electrochemical impedance spectroscopy, cyclic voltammetry, conductivity measurements, electron spin resonance and FT infrared spectroscopy. Conclusively the behaviors of PEDOT in the three potential regions were distinctly different. The process in p-doping region was reversible doping/dedoping process, which kept the conjugated structure, conductivity and functional group. The process in transitional region resulted in the change of functional group but invariation of the conjugated structure and conductivity of PEDOT. The process in overoxidative part was badly destructive, which resulted in the irreversible change of the conjugated structure, conductivity and functional group.