PREPARATION AND CHARACTERIZATION OF AQUEOUS POLYANILINE DISPERSIONS

Stable aqueous dispersions of polyaniline (PANI) have been prepared us ing an underivatized poly(vinyl alcohol-co-acetate) (PVAL) as a steric stabilizer. Investigation of aqueous PANI dispersions by scanning ele ctron microscopy and light scattering revealed that oxidative polymeri zation of aniline in the presence of PVAL results in the formation of spherical particles. Their size does not depend on the concentration o f aniline in the polymerizing system but the uniformity of the particl es seems to be improved as the aniline concentration is increased at l east up to a certain limit. Electron absorption spectroscopy study of PANI dispersions made it possible to follow the changes of PANI on bot h molecular and supermolecular levels. When the initial concentration of aniline in the polymerizing system was ca 2 wt% (at a concentration of PVAL from 2 to 10 wt%), electrical conductivity of free standing f ilms cast from dispersions reached 10(-1)S/cm.