دانلود رایگان ترجمه مقاله سنتز الکتروشیمیایی و ویژگی های کلرید دوپ شده با پلی آنيلين (نشریه اسپرینگر 2003)

سنتز الکتروشیمیایی و ویژگی های کلرید دوپ شده با پلی آنيلين

Electrochemical synthesis and characterization of chloride doped polyaniline

Abstract

Chloride doped polyaniline conducting polymer films have been prepared in a protic acid medium (HCl) by potentiodynamic method in an electrochemical cell and studied by cyclic voltammetry and FTIR techniques. The FTIR spectra confirmed Cl- ion doping in the polymers. The polymerization rate was found to increase with increasing concentration of aniline monomer. But the films obtained at high monomer concentration were rough having a nonuniform flaky polyaniline distribution. Results showed that the polymerization rate did not increase beyond a critical HCl concentration. Cyclic voltammetry suggested that, the oxidation-reduction current increased with an increase in scan rate and that the undoped polyaniline films were not hygroscopic whereas chloride doped polyaniline films were found to be highly hygroscopic.

1 Introduction

Research in electroactive polymers, particularly in aromatic conducting polymers, has received considerable attention worldwide in the past few years because of their potential applications in the fields of microelectronics, optics and optoelectronics (Bernard et al 1998, 2001; Schultze et al 1999; Mousty et al 2001). Among these polymers, polyaniline (PAni) is one of the most widely studied conducting polymers because of its good conductivity that can be influenced both by the charging level and degree of protonation, its well defined electrochemical (redox) response, easy preparation and possible applications in rechargeable batteries, corrosion protection, light emitting diodes, molecular sensors, electrochromic devices and microwave screening (Inzelt et al 2001). Polyaniline is not charge conjugation symmetric, i.e. the valence and conduction bands are asymmetric to a great extent (Ghos et al 2001). A partial oxidation of PAni usually leads to the reorganization of bonds, resulting in an increase in electronic conductivity. The physicochemical properties of PAni are strongly related to the proportion of aryl amine and quinone imine units present (Genies et al 1988). PAni possesses two voltammetric redox pairs including three stable oxidation states, with the half-oxidized state (emaraldine) being highly conductive in its protonated state. Existence of different oxidation states of PAni makes it useful as an electrode material in electrochemical capacitors (Robberg et al 1998; Fusalba et al 2001; Hu and Chu 2000, 2001).

In the present study polyaniline films have been prepared by electropolymerization from an electrolyte containing HCl and aniline monomer at different concentration ratios. The polymer films have been studied by cyclic voltammetry. FTIR spectra have been recorded for confirmation of Cl– ion doping of the polymer films.