Electrosynthesis and optical characterization of poly(p-phenylene), polypyrrole and poly(p-phenylene)-polypyrrole films

Abstract

Poly(p-phenylene) (PPP), polypyrrole (PPY), and poly(p-phenylene-pyrrole) (PPP-PPY) films were electrochemically synthesized in acetronitrile by cyclic voltammetry. For comparison purposes, the films were characterized by cyclic voltammetry in a monomer-free solution, and their optical responses were also obtained in the UV-VIS range of energy after varying the applied potentials. The absorbance spectra of the PPP-PPY film exhibited bands typically seen in the spectra of the homopolymers, PPP and PPY films, but better defined, intense, and related to reversible color transitions. Although it was not possible to confirm by using infrared and Raman spectroscopy that a copolymer was in fact obtained, the presence of both monomers, pyrrole and biphenyl, in the polymerization medium turned easier the process of film formation, yielding darker, more uniform, and rougher films as it was verified by photographic images and AFM (atomic force microscopy) images.