Constructive modification of conducting polyaniline characteristics in unusual proportion through nanomaterial blend formation with the neutral polymer poly(vinyl pyrrolidone)

The present work reports an investigation on the modification of conducting polyaniline (PANI) characteristics favorably on blending with the neutral polymer, poly(vinyl pyrrolidone) (PVP) in a systematic variation of their molar ratios (aniline : PVP = 4 : 1, 2 : 1, 1 : 1, 1 : 2, and 1: 3). Prepared by precipitation technique by conventional in situ chemical oxidative polymerization with ammonium peroxodisulfate in aqueous H2SO4 medium (pH 1.0), these materials have nanometer sizes (similar to 50-200 nm) and, depending on the molar ratios, exhibit a distinct deviation in physicochemical characteristics from those of pristine PANI prepared in the identical condition. A gradual trend in characteristics is noticed in first three PANI-PVP blends, while an abnormal hike in conductivity, unusual spectral features in IR and UV-vis, hardened nature, and induction of characteristic morphology, crystallinity, and thermal stability are associated with the last two blends that have excess PVP. Thus a division of two sets of nano-blends, one set with less or equal content of PVP and another with excess of PVP, emerges. Evidently, PVP has a tuning effect on PANI through its dopant, supporting matrix and interpenetrating steric stabilizer acts in proportion quite unusual to its neutral nature. The study altogether brings to light a simple way of modification of PANI characteristics by conventional method of blend synthesis. (c) 2007 Wiley Periodicals, Inc.