电化学法制备高密度导电聚吡咯的性能研究

系统地研究了溶剂、温度和聚合电流密度对电化学制备本征导电聚吡咯 (PPy)膜密度的影响,分别用四探针法和热失重(TG)法研究了不同密度的PPy膜的电导率和热稳定性.用循环伏安法(CV)和电化学阻抗谱(EIS)法比较了不同密度的PPy膜的电化学性能.研究表明,在室温下,在乙氰/水(AN/H₂O, 99/1)溶液比在水溶液中容易得到高密度的PPy膜.高聚合电流密度(如10mA/cm²)可以进一步提高PPy膜的密度,用X射线光电子能谱(XPS)对其结构进行了分析.在AN/H₂O(99/1)溶液中用小电流密度(0.1mA/cm²)聚合时,低温(-20℃)有利于提高PPy膜的密度;然而在高电流密度(10mA/cm²)时, 低温(-20℃)不利于提高PPy膜的密度.高密度的PPy膜(1.42g/cm³)用电流密度10mA/cm²在0℃的AN/H₂O(99/1)溶液中制得.该合成方法和常用的低温低电流密度方法制备高密度的PPy膜相比, 合成时间短,条件易实现,更利于实用化.更重要的是,高密度的PPy膜不仅具有高电导率(～220S/cm)和高热稳定性,还具有低的电化学活性.因此,高密度的PPy膜不仅是一种优异的电子导电的电极材料,而且是一种潜在的优异的防腐材料.关键词：聚吡咯膜密度电导率热稳定性

Properties of electropolymerized high density polypyrrole films

The high density PPy films (HD-PPy，ρ>1.4g/cm³) doped with p-toluenesulfonate (TOS^-) counterions were electropolymerized by a facile approach in H₂O and acetonitrile (AN) mixed solvent. The structure and electrochemical properties of the HD-PPy films were measured by X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) analysis, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that appropriate ratio of AN/H₂O (99/1) could be favorable to increase the density of PPy films. Further enhancement of the density could be obtained by using higher current density (such as 10mA/cm²), as it favors the formation of two-dimensional structure. Generally, low temperature of polymerization, T_p (e.g. -20℃), is advantageous to the enhancement of density and conductance of PPy films. But if T_p is too low, it beesmes disadvantageous in case of the high current density of polymerization. The HD-PPy films (1.42g/cm³) were obtained at 0 ℃ with 10mA/cm² in AN/H₂O(99/1) solution. Furthermore, HD-PPy films were characterized not only by high electronic conductivity (～220S/cm) and high thermal stability, but also by low electrochemical activity. It was indicated that the HD-PPy would be not only an excellent electrode material but also a promising corrosion protection material.