Polypyrrole production through chemical polymerization using anionic and cationic dopants: The influence of synthesis conditions and reaction kinetics

Abstract

The aim of this study was to use gravimetric analysis to assess the kinetics of chemical polymerization of pyrrole in water, applying ferric chloride as oxidant. The influence of temperature, the concentration of FeCl3.6H2O, and the presence of different types of dopants (two anionic, one cationic, and one ionic liquid) on conversion, morphology, thermal stability, and conductivity of polypyrrole was investigated. The results showed a conversion close to 90 % at 20 °C with 0.5 M of FeCl3.6H2O and increased above 100 % with the addition of DBSA, due to its incorporation in the polymer chain. The polypyrrole nanoparticles had average sizes of 360 nm at 5 °C and 320 nm at 20 °C. Both of the dopants, SDS and C12MimCl, stabilized the nanoparticles. The use of SDS conferred an electrical conductivity of 13.30 S cm-1 to the polymer. Finally, the kinetic model (two fast sequential reactions, i.e., consumption of pyrrole via an oxidation reaction and reaction with oxidized oligomers) satisfactorily fitted the experimental data (with R2 > 0,9).