Polymerisation and characterisation of conducting polyaniline nanoparticle dispersions

Micellar emulsion chemical polymerisation of polyaniline (PANI) using dodecylbenzenesulfonic acid (DBSA) as the micelle and dopant was performed at 20degreesC. It was necessary to use a ratio of 1: 1: 1 for aniline, oxidant (ammonium persulfate APS) and DBSA to produce the PANI.DBSA in the emeraldine salt (ES) form in large quantities (40 g). The resulting polymer was a nanodispersion with spherical particles 10+/-2 nm in diameter and an electrical conductivity of 15+/-3 S cm(-1) as determined by transmission electron microscopy (TEM) and the four-point probe method, respectively. UV-vis spectral characterisation showed the nanodispersion to be highly doped. Complete deprotonation of the polymer to the emeraldine base form using 0.5 M NaOH was only possible upon dilution to approximately 0.05% w/v polymer. Reduction of the polymer to leucoemeraldine using phenylhydrazine was relatively slow; however, oxidation to pernigraniline in 0.25 M APS occurred instantaneously. (C) 2003 Published by Elsevier B.V.