Oxidation of Aniline with Silver Nitrate Accelerated by p-Phenylenediamine A New Route to Conducting Composites

The reaction between two nonconducting compounds, aniline and silver nitrate yields a composite of two conducting products PANI and silver While the oxidation of aniline with silver nitrate is slow and takes over several months, the addition of a small amount of p phenylenediamine, 1 mol % relative to aniline, shortens the reaction time to a few hours and, with higher concentrations of p-phenylenediamine even to tens of minutes Nonconducting aniline oligomers, however, are also present in the oxidation products as a rule The chemistry of individual oxidation pathways is discussed Higher concentrations of p phenylenediamine in the reaction mixture with aniline give rise to copolymers poly[aniline-co (p-phenylenechamine)]s and their composites with metallic silver p-Phenylenediamine alone can similarly be oxidized with silver nitrate to poly(p phenylenediamine) composite with silver Silver is present in the composites both as nanoparticles of similar to 50 nm size and as larger objects The composites have conductivity in the range of the order of 10(-3)-10(3) S cm(-1) at comparable content of silver, which was close to the theoretical expectation, 68 9 wt % The composites prepared in 1 M acetic acid always have a higher conductivity compared with those resulting from synthesis in 1 M nitric acid The polymerizations of aniline accelerated with 1 mol % of p-phenylenediamine in 1 M acetic acid yield a composite of the highest conductivity 6100 S cm(-1) At higher contents of p phenylenediamine, poly[aniline-co-(p-phenylenediamine)] composites with silver have a conductivity lower by several orders of magnitude The oxidation of p phenylenediamine alone with silver nitrate in 1 M acetic acid also yields a conducting composite, its conductivity being 1750 S cm(-1) The semiconductor type of conductivity in polymers and the metallic type of conductivity in silver may compensate to yield composites with conductivity nearly independent of temperature over a broad temperature range