Electrochemical Polymerization of Aniline in Proton-Free Nonaqueous Media

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; 共i兲 sodium tetraphenylborate 共TPB兲, 共ii兲 tetraethylammonium tetrafluoroborate 共TETFB兲, and 共iii兲 tetramethylammonium perchlorate 共TMAP兲 are chosen for electrpopolymerization of aniline under potentiostatic mode 共2V vs. Ag/AgCl兲 and potentiodynamic mode 共⫺0.7 to 2.0 V vs. Ag/AgCl at the scan rate of 100 mV/s兲. Polyaniline films with seven different microstructures 共polymer I to polymer VII兲 are synthesized. Polymer I and polymer II are made under potentiostatic condition in acetonitrile and dichlo- romethane containing 0.1 M sodium tetraphenylborate 共TPB兲 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 共TETFB兲, whereas polymer VII is made under similar conditions in acetonitrile containing tetramethylammonium perchlorate 共TMAP兲. 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. ©