Polyaniline-silver composites prepared by the oxidation of aniline with mixed oxidants, silver nitrate and ammonium peroxydisulfate: The control of silver content

Aniline was oxidized with mixtures of two oxidants, ammonium peroxydisulfate and silver nitrate, to give polyaniline-silver composites with variable content of silver in the composites. The presence of peroxydisulfate has a marked accelerating effect on the oxidation of aniline with silver nitrate. Oxidations in 1 M methanesulfonic acid produced composites in high yield. The molecular structure of the polyaniline was confirmed by UV-visible and FTIR spectra, and the polymeric character was established by gel-permeation chromatography. The content of silver varied between 0 and 70 wt.%. The silver nanoparticles were smaller than 100 nm. The conductivity of the composites was of the order of units S cm(-1). Only at high silver nitrate contents in the reaction mixture, the conductivity of products exceeded 100 S cm(-1). The conductivity of the composites sometimes increased after deprotonation of the polyaniline salt to a non-conducting base. Such conductivity behaviour is discussed in terms of the percolation model. (C) 2011 Elsevier Ltd. All rights reserved.