ETHYL(HYDROXYETHYL)CELLULOSE STABILIZED POLYANILINE DISPERSIONS AND DESTABILIZED NANOPARTICLES THEREFROM

Ethyl(hydroxyethyl)cellulose (EHEC) has been used as a stabilizer for the dispersion polymerization of aniline in water and in aqueous ethan ols. An increasingly greater amount of aniline could be used to prepar e the dispersion as the ethanol concentration increased in the medium over the range 50-70 vol %. EHEC incorporation in the particles increa ses and particle size decreases with an increase in the ethanol concen tration under otherwise identical experimental conditions. Particles p repared in aqueous ethanols and containing less than ca. 8 wt % EHEC a re easily disintegrated to nanoparticles (similar to 20 nm) using ultr asound. These nanoparticles are unstabilized and undergo fractal aggre gation even in a medium that contains a substantial amount of EHEC. Th is fact suggests that in the dispersion polymerization the real stabil izer is not the homopolymer EHEC but could be its graft copolymer. The fractal dimension (D) of the aggregates lies in the range 1.69-1.89. These values agree well with the theoretically determined values of D obtained by computer simulation based on a cluster-cluster aggregation model in three dimensions.