Study On Electrochemical Synthetic Polythiophene And Poly(Paraphenylene) Film And Their Electrochemical Performances

Polythiophene(PTH) and poly(paraphenylene)(PPP) are two typical conducting polymers. Owing to good conductivities and environmental stabilities, they are prospective candidates as the function materials in the application fields of power, luminescence, sensor, corrosion protection and so on.The electrochemical synthetic method become the main way to prepare the PTH and PPP film for these two conducting polymer films can be directly formed on the electrode surface and the thickness and conductivity of the films can also be controlled. The conformation of electrodeposited films will affect the properties of the conducting polymer films. Besides, the conformation of the film should be determined by various electrochemical conditions. Hence, study on conformation of the conducting polymer film has important practical value to improve the properties of the film.In this article, polythiophene and polyparaphenylene films were prepared both on inert electrodes and 304 stainless steel by electrochemical methods. The film structure and electrochemical properties were investigated. Besides, the conformation of the two films was described by fractal methods. The results were as follows:PTH and PPP films were prepared both on Pt, glass carbon and conducting glass(ITO) electrodes by electrochemical methods. Both PTH and PPP films owed order structure and reversible electrochemical properties. The conductivities of PTH and PPP film was in 5-10S/cm and 2.0-5.0S/cm range, respectively. Based on the electrodeposition of PTH and PPP film, gray analyze was introduced to study the micrographs of the two film. The fractal characteristic of the two films was identified from the analyzed results. Fractal features were found for electrodeposition charge density of 100mC/cm~2 and 10mC/cm~2 PTH films were 2.885 and 2.787, respectively. The difference indicated that the thin and thick film of PTH had different fractal structure. The effects of potentail conditions on the fractal structure of PTH and PPP films were studied by electrochemical impedance method. In the potential range (0-0.6V), the film surface fractal dimension rised with doping level.A bilayer coating was prepared on 304 stainless steel by electrodeposition of a polybithiophene film on top of a square wave passivated 304 stainless steel electrodes by electrochemical methods. The PTH layer had order structure and reversible electrochemical properties. The conductivity of PTH film was in 5-1 OS/cm range. The interfacial shear strength of the 304SS/AV800/PTH and 304SS/AV1020/PTH was found to be 4.98MPa and 5.10MPa. Electrochemical properties of the coating were investigated in 1M H2SO4 solution by polarization and electrochemical impedance spectroscopy measurements. The results indicated that the bilayer could provide an effective barrier and maintain the metal substrate in passive state during the considering immersion time.A PPP film was successfully prepared on a square wave passivated 304 stainless steel electrodes by electrochemical methods. The PPP layer had order structure and reversible electrochemical properties. The conductivity of PPP film was in 1.0-3.0S/cm range. The interfacial shear strength of 304SS/AV1020/PPP film was found to be 4.65MPa...