Electrochemical Synthesis of Polypyrrole Layers Doped with Glutamic Ions

Electrochemically synthesized polypyrrole thin films doped with glutamic ions were investigated as interesting materials for potential use as molecularly selective surfaces. Pyrrole and glutamate interact in aqueous solution, resulting in the formation of a prominent band at 240 nm in the absorption spectra of the solution. This feature was assigned to the formation of a complex, which significantly influences the electrochemical deposition of polypyrrole films doped with glutamate. It was also detected that oxidation of these complexes leads to the appearance of a shoulder in the absorption spectrum at 270 nm, which corresponds to the yellowish color of pyrrole aged under influence of air. A mechanism is proposed for polymer film growth in aqueous solutions containing monosodium L-glutamate and pyrrole. It takes into account the observed influence of the pH of the solution, the concentration of reagents, the zwitterionic properties Of glutamate on deposition, and results from spectroscopic measurements. It is also shown that glutamic ions can electrochemically be released from the synthesized polymer layers. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 4051-4058, 2009