Development of Self-Doped Conducting Polyaniline Bearing Phosphonic Acid Moiety

Abstract

In this comprehensive paper, syntheses and properties of self-doped conducting polyanilines bearing phosphonic acid moieties are summarized. Poly(2-methoxyaniline-5-phosphonic acid) (PMAP), a polyaniline bearing phosphonic acid moieties which are directly bonded to the main chain, was synthesized by oxidative polymerization of 2-methoxyaniline-5-phosphonic acid. The synthesis could be scaled up by improving the synthetic scheme. Poly(2-methoxyaniline-5-phosphonic acid monoester) (PMAPE), a monoester form of PMAP, was also synthesized. Self-doping of PMAP and PMAPE was confirmed from their absorption, ESR, and XPS spectra. The conductivity of PMAP and PMAPE was 1.9 × 10⁻¹ and 1.0 × 10⁻² S/cm, respectively. Unlike a typical conducting polyaniline, PMAP showed the efficient delocalization of polarons under basic conditions (ca. pH 10). We also achieved to prepare the self-doped conducting polyaniline that is soluble in organic solvents by forming salts with quaternary ammonium cations possessing long alkyl chains. PMAP exhibited properties that make it useful as an antistatic agent in electron beam lithography.