Preparation and evaluation of polyaniline and polypyrrole modified water‐dispersible conducting nanocomposites of polyacrylonitrile with silica

Water‐dispersible conducting nanocomposites were prepared by precipitating polyaniline (PANI)/polypyrrole (PPY) in an aqueous suspension of polyacrylonitrile–SiO 2 (PAN–SiO 2 ) via K 2 CrO 4 –NaAsO 2 redox polymerization. Incorporation of PANI and PPY in the composites was confirmed by the FTIR spectrum. Scanning electron microscopic analyses for the PANI–(PAN–SiO 2 ) and PPY–(PAN–SiO 2 ) composites indicated formation of lumpy aggregates with irregular sizes. TEM analyses revealed formation of spherical particles with size ranging between 80 and 150 nm for PANI–(PAN–SiO 2 ) nanocomposite and 75–150 nm for PPY‐(PAN‐SiO 2 ) nanocomposites, respectively. Thermal stabilities of the PANI–(PAN–SiO 2 ) and PPY–(PAN–SiO 2 ) nanocomposites were higher than those of the individual base polymers. Conductivity values of PANI–(PAN–SiO 2 ) nanocomposite (10 −3 S cm −1 ) and PPY–(PAN–SiO 2 ) nanocomposite (10 −4 S cm −1 ) were remarkably improved relative to that for PAN homopolymer (>10 −11 S cm −1 ). Both of these composites produced a permanently stable aqueous suspension when the polymerization was conducted in presence of nanodimensional SiO 2 as a particulate dispersant. Copyright © 2004 Society of Chemical Industry