Electrochemical Polymerization of Aniline in Proton-Free Nonaqueous Media: Dependence of Microstructure and Electrochemical Properties of Polyaniline on Solvent and Dopant

Abstract

Electrochemical polymerization of aniline in few nonaqueous media containing varying supporting electrolytes is reported. Three different nonaqueous solvents, i.e., dry acetonitrile, dichloromethane, and nitrobenzene containing three different electrolytes; sodium tetraphenylborate (TPB), tetraethylammonium tetrafluoroborate (TETFB), and tetramethylammonium perchlorate (TMAP) are chosen for electrpopolymerization of aniline under potentiostatic mode (2 V vs. Ag/AgCl) and potentiodynamic mode to 2.0 V vs. Ag/AgCl at the scan rate of 100 mV/s). Polyaniline films with seven different microstructures (polymer I to polymer VII) are synthesized. Polymer I and polymer II are made under potentiostatic condition in acetonitrile and dichloromethane containing 0.1 M sodium tetraphenylborate (TPB) and tetraethylammonium tetrafluoroborate, respectively, whereas polymer III is made under similar conditions in acetonitrile containing 0.1 M tetraethylammonium tetrafluoroborate. Polyaniline films of four other microstructures are made under potentiodynamic mode of electropolymerization. Polymer IV, polymer V, and polymer VI are synthesized in acetonitrile, dichloromethane, and nitrobenzene, respectively, containing the same supporting electrolyte, i.e., 0.1 M tetraethylammonium tetrafluoroborate (TETFB), whereas polymer VII is made under similar conditions in acetonitrile containing tetramethylammonium perchlorate (TMAP). The microstructures of polyaniline films are characterized by scanning electron microscopy and cyclic voltammetry. The results show varying microstructures of the films with change in the nature of electroactivity from polymer I to polymer VII. The comparative results on pH sensitivity are reported. © 2002 The Electrochemical Society. All rights reserved.