Preparation Of Conductive Polymer Composite Film And Investigation Of Their Characteristic

As a new composite material, conducting polymer composite film has electrical and optical properties of metal and inorganic semiconductor and flexile mechanical performance and processibility of organic polymer as well as electrochemical redox activity. These properties are favorable to its applications in electrode material of rechargeable batteries, conversion of light to electricity, electromagnetic shielding, Electrocatalysis, electrochemical sensor and corrosion protection. Therefore the method of directly preparing conducting polymer composite material has being attracted much attention. In this paper we report the synthesis of PANI/CA, PANI/ PSF and PPy/CA composite films with porous structure by using new polymerization methods, namely a phase separation and in-situ polymerization. The surface morphology, the chemical structure and electrical properties of the composite films were investigated in detail. The main results are summarized as following:Conductive PANI/CA composite films were prepared by phase separation and in-situ chemical polymerization with APS as oxidant in dilute hydrochloric acid. An advantage of this method was formation of the films and the oxidation polymerization of the aniline occurred simultaneously. The prepared condition has evidently influenced on conductivity of the films. The optimum conditions for preparing PANI/CA films are as following: the aniline concentration is 0.13(V/V), the molar ratio of APS to aniline is 0.4, the reaction temperature is at 5 ℃ and reaction time is about 4 min. FTIR spectra and SEM and AFM images indicated the face and the back of the composite film had different chemical component and an asymmetric porous structure. The face of the composite film is composed of ployaniline layer with irregular pores, while the back consists of cellulose acetate with granular structure. The thermogravimetric analysis indicates that the thermal stability of the PANI/CA film is higher than that of the pure CA film. In addition, annealing temperature has also greatly influenced on conductivity of the films, when the temperature is higher 120℃, resistance of the films sharply increased.Aniline solution was coated evenly on the surface of the electrode under self-driving force, the PANI/PSF composite film was prepared by cyclic voltammetryin 0.5MH2SO4. An advantage of this method was that the conductive layer of the composite films adhered to the polysulfone membrane tightly; the film can be easily peeled. FTIR spectra and SEM images presented that the composite film had an asymmetric porous structure. The face of the films is ployaniline layer with irregular pores, while the back is polysulfone layer with a sponge-like structure. Investigation of electrochemistry showed that the replicated composite film exhibits repeatability under quantitatively controlling. The relative average deviation of peak currents is about 3.87%. Both solute concentration and counter ion property in solutions have the significant effect on redox peak current of polyaniline. The composite film had catalytic activity for the oxidation of AA because it leaded to an obvious negative shift of AA oxidation peak potential. In the conducting state, the impedance spectra of the composite films shows a semi-circle in the high frequency region and a straight line with a slope of nearly 45° in the low frequency region, which is due to the Warburg diffusion impedance. In oxidation state, the impedance spectra of the composite films indicates a 1/2 semi-circle in all frequency region, which exhibits a higher electrochemical charge transfer resistance. In addition, an equivalent electric circuit is done by the experimental impedance spectra.Polypyrrole/cellulose acetate composite films were prepared by phase separation and in-situ polymerization with FeCl3 as oxidant in aqueous medium. The surface morphology and chemical component were charactered by AFM and FTIR. It was found that the face of the films were composed of polypyrrole with a cluster-like structure, the back consisted of cellulose acetate with gran...