电化学法制备高密度导电聚吡咯的性能研究

Properties of electropolymerized high density polypyrrole films

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.

The high density PPy films （HD-PPy,ρ 〉 1.4 g/cm^3） doped with p-toluenesnlfonate （TOS-） counterions were electrepolymerized 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/cm^2 ）, as it favors the formation of two-dimensional structure. Generally, low temperature of polymerization, Tp （e. g. - 20℃）, is advantageous to the enhancement of density and conductance of Play films. But if Tp is too low, it beesmes disadvantageous in case of the high current density of polymerization. The HD-PPy films （ 1.42 g/cm^3 ） were obtained at 0 ~C with 10 mA/cm2 in AN/H20（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 premising corrosion protection material.