Characterization of Polyaniline and Poly(m-toluidine)-based Nanoparticles of Ultranarrow Particle Size Distribution

Abstract

The oxidative polymerization of aniline or m-toluidine, carried out in concentrated solutions of poly(vinyl alcohol-co-acetate) (PVA), was used to prepare colloidal composite particles of polyaniline-PVA or poly(m-toluidine)-PVA of ultranarrow particle size distribution and of controlled average particle size. The particle size distributions were measured by quasi-elastic light scattering in diluted polymerization products. Such a measurement can be influenced by undestroyed PVA aggregates formed in the initial solution. The aim of this work was to determine conditions under which the true particle size distribution of the composite particles can be measured or, at least, estimate the degree such a determination is influenced by PVA aggregates not incorporated into the composite particles. Quasi-elastic light scattering measurements of the diluted polymerization products were carried out under various experimental conditions. The composite particles were separated from the PVA solution by centrifugation and redispersed in water. The size of the redispersed composite particles and of the PVA aggregates in the supernatant solution was measured again by quasi-elastic light scattering. Scanning electron microscopy showed the spherical shape of the synthesized composite particles and confirmed their ultranǎrrow size distribution.