Analysis And Characterization Of The Electrochemical Properties Of The Polyaniline Material Synthesized By Emulsion Polymerization

Conducting polymers receive a wide concern because of their demonstrated device application. Among the family of conducting polymers, polyaniline (PANI) is one of the most interesting conducting polymers due to its inherent conductivity, reversible redox and optical properties. Currently, it has been widely used in basic materials, such as pH-sensors, biosensors, rechargeable batteries, membranes, electrochromic displays and corrosion-protecting coating.In the past decades, coating methods is the primary means to characterize electrochemical properties of the PANI synthesized by chemical polymerization. Due to the characteristics of high conductivity, stable chemical performance, small pore size, large surface and electrochemical inactivity of carbon paper, therefore, using the carbon paper loaded PANI as electrode material, which can solve the problems of lower solubility, infusibility, homogeneity of membrane of the PANI and non-conductive film former.In the present work, the carbon paper is firstly used as a vector to add to the emulsion polymerization, and a uniform, continuous, dense PANI film is formed on the carbon paper in the polymerization. The carbon paper loaded PANI is used as working electrode to characterize the electrochemical properties of the PANI, which can solve the problems of sensitivity, accuracy and stability in characterization and analysis of the electrochemical properties of the PANI. PANI and PANI/acetylene black (PANI/AB) composite doped with dodecylbenzenesulfonic acid (DBSA) were prepared by emulsion polymerization using ferric chloride (FeCl₃) and ammonium persulfate (APS) (FeCl₃/APS) as composite oxidant. A method takes the carbon paper loaded PANI and the carbon paper loaded PANI/AB composite as working electrode to real-time characterize and analyze the electrochemical properties (cyclic voltammogram and Tafel curve) of the PANI and PANI/AB composite. The characterization results of the electrochemical properties of the products have been proved by contrast analysis of conductivity, yield, FT-IR, XRD and TGA of the products.The experimental results indicated: (1) The PANI with the best properties when the molar ratio of FeCl₃ to APS is 3.5:1, the molar ratio of FeCl₃/APS composite oxidant to aniline (An) is 3:1, the reaction time is 8h and the molar radio of DBSA to An is 0.8:1. The properties of the PANI prepared in this condition were compared to that of the PANI oxidized by APS: the peak current of cyclic voltammetry, corrosion potential, conductivity and yield were higher, and its crystallinity and thermal stability are also improved. (2) The PANI/AB composite with the best properties when the content of acetylene black is 5%, the molar radio of FeCl₃/APS composite oxidant to An is 3:1, the reaction time is 8h and the molar radio of DBSA to An is 0.8:1. The properties of the PANI/AB composite prepared in this condition were compared to that of the PANI prepared in the same condition: the peak current of cyclic voltammetry, corrosion potential and conductivity were bigger. The microstructure characterization results showed that the crystallinity and the thermal stability of the PANI/AB composite were also improved.The experimental results showed that FeCl₃/APS composite oxidant can improve the properties of the PANI, which indicated that FeCl₃/APS composite oxidant can be used as an ideal composite oxidant to prepare PANI. The properties of the PANI/AB composite were also improved compared to that of the PANI, showing that there is a unique advantage in the PANI composite.