The Effect Of Oxidant On Structure And Electrochemical Properties Of PAn/PTFE Conducting Composite Membrane

As a novel functional material, conducting polymer has special physical and chemical properties, which suggests promising application in many fields such as energy sources, photoelectron parts of an apparatus, sensor, molecule parts of an apparatus, metal antisepticise etc.Therein, polyaniline (PAn) shows favorable properties, such as environmental stability, high conductivity, structure diversity, low-production cost. By the means of combining the polyaniline with other special materials, it can enhance the machining ability of polyaniline, and furthermore may produce a lot of useful composite materials.Consideration of the molecule structure of polyanilineand substract membrane, the in-situ synthesis of conducting composite membrane of polyaniline with commercial microporous polytetraflouroethylene(PTFE) was described, used ammonium persulfate, sodium Orthovanadate and Ferric chlorideas as oxidants respectively. Also, the effect of different polymerization conditions on the conductivity and pour size was studied and the optimum polymerization conditions were obtained.In the second part of this paper, the pore size and distribution of the PAn/PTFE compsite membrane was determined and evaluated by bubble pressure and liquid permeation method. And by SEM, surface morphology of PAn/PTFE composite membrane was studied. The conducting performance was examined by four-probe method and the range of conductivity distribution was measured. Moreover, the mechanism of composition was also suggested by comparing FT-IR spectra of PTFE substract membrane and all three types of PAn/PTFE composite membranes. In addition, the electrochemical capability was examined in three electrodes system by cyclic voltammetric method and AC impedance method respectively.The result suggested that the resulting composite membrane polymerized with Na₃VO₄ had smallest average pore radius than that of the others, and it had the most polymers in its pores. Furthermore, the PAn/PTFE composite membrane polymerized with Na₃VO₄ possessed the characteristic of high surface conductivity and cross-sectional conductivity, and showed the best electrochemical activity.