The Preparation and Characterization of Colloidal Polypyrrole

This paper describes the preparation and properties of colloidal polypyrrole. The polypyrrole was prepared by the oxidation of pyrrole with potassium persulfate in acidic, 25% aqueous, ethanol at 95°C. Absorption spectra showed that the reaction produced both unoxidized polypyrrole (ppy0) and oxidized polypyrrole ( ppy +), which were separated by precipitating the ppy + with water. The resulting ppy + was readily redispersed in ethanol to yield a strongly coloured , transparent, dispersion. Cyclic voltammetry of the dispersion yielded well defined peaks for reduction and reoxidation with a standard reduction potential of approximately -0.39 V v . s.c.e . The ppy + was also characterized by fluorescence spectroscopy, proton magnetic resonance spectroscopy and electron microscopy.