Electrically Conductive Nanocomposites of Polyaniline with Poly(vinyl alcohol) and Methylcellulose

Electrically conductive nanocomposites of HCl-doped polyaniline (PANI-HCl) nanocolloid particles with water-soluble and film-forming polymers such as poly(vinyl alcohol) (PVA) and methylcellulose (MC) were prepared by the redispersion of preformed MC-coated submicrometric PANI-HCl particles in PVA and MC solutions under sonication for I h and the casting of the films from the dispersions followed by drying. The submicrometric polyaniline (PANI) particles were prepared by the oxidative dispersion polymerization of aniline in an acidic (1.25M HCl) aqueous ethanol (30 : 70) medium with MC as a steric stabilizer. The particles contained 4.7 wt % MC and had a conductivity of 7.4 S/cm. They had an oblong shape of 203 nm (length) and 137 nm (breadth). Sonication broke the oblong-shaped particles to sizes of similar to 10 nm in the PVA matrix and similar to 60 nm in the MC matrix. The electrical conductivity of these films was measured, and the percolation threshold was determined. The composites had the characteristics of a low percolation threshold at a volume fraction of PANI of 2.5 X 10(-2) in the PVA matrix and at a volume fraction of 3.7 x 10(-2) in the MC matrix. (C) 2008 Wiley. Periodicals, Inc. J Appl Polym Sci 2008