Cationic polypyrrole composites with anionic functional molecules

Abstract

Positively charged pyrroles incorporating the quaternized pyridine moiety, [1-methyl-3-(pyrrol-1-ylmethyl)pyridinium chloride, MPP] and [1-(5-pyrrol-3-ylpentyl)pyridinium bromide, PPP], have been synthesized. The polymer of MPP (PMPP), cationic polypyrrole obtained by chemical polymerization and electropolymerization of MPP, is soluble in various polar solvents and displays anion-exchange ability. The amount of the incorporated anionic species in PMPP is ca. five times greater than that in polypyrrole because incorporation is through anodic doping and electrostatic binding with the pyridinium moiety. The PMPP composites with anionic metal complexes and anionic polymers provide films either by the casting method or by the dipping method. These films were also obtained by electropolymerization of MPP in the presence of the anionic functional molecules. The resulting composite-modified electrodes show clear electrochromism (EL) for PMPP/FeBPS and bright electrogenerated chemiluminescence (ECL) for PMPP/RuBPS, respectively. Excellent optical properties are achieved by incorporation of a large amount of the anionic functional molecules and therefore by suppression of undesired background absorption of the PMPP matrix. Another cationic polymer of PPP showed high conductivity (10^–2 S cm^–1) as well as high-density incorporation of anionic functional molecules.