SYNTHESIS OF NOVEL POLYANILINE COLLOIDS USING CHEMICALLY GRAFTED POLY(N-VINYLPYRROLIDONE)-BASED STABILIZERS

We report the synthesis of polyaniline colloids using a new polymeric steric stabilizer based on a poly(N-vinylpyrrolidone) copolymer. This copolymer stabilizer contains pendant aniline groups which are believed to participate in the in situ aniline polymerization, leading to the chemical grafting of the stabilizer onto the surface of the polyaniline particles. The stabilizer is compatible with both (NH4)2S2O8 and KIO3 oxidants and so represents an improvement over our earlier work. Our electron microscopy studies have confirmed that the polyaniline colloid morphology depends on the oxidant used for the aniline polymerization. Thus the (NH4)2S2O8 oxidant produces spherical particles while the KIO3 leads to the formation of "rice-grain"-shaped particles. The mass ratio of grafted stabilizer/polyaniline has been indirectly determined by assaying postreaction supernatant solutions by colorimetry using congo red dye as a complexing agent. The polyaniline colloids were further characterized by a wide range of techniques including FTIR and visible absorption spectroscopy, microanalysis, dc conductivity, and thermogravimetric analysis. © 1992.