Proton acid doping and conductivity decay of poly N-methylpyrrole

摘要

A study of conducting poly N-methylpyrrole (PNMPy)/ClO4 films electrochemically synthesized in acetonitrile solution has been carried out. Films immersed in aqueous solutions of increasing pH were examined by FTIR spectroscopy. The IR spectrum, yellow color, and low conductivity indicate that polymer changes to the non-conducting form in basic medium. However, film conductivity is recovered after a new immersion in acid solution. This points to the existence of a proton doping mechanism in PNMPy/ClO4 confirmed by the infrared spectrum and by the conductivity changes observed after acid immersion. However no new NH or CH bonds are observed in the spectra of these films, which indicates that protons in the film seem to be "free". Stabilization in air of basic-acid treated films is observed since conductivity of these films remains higher than 10(-4) S cm(-1) for more than 400 h. Conductivity decay with ageing time has also been determined as a first order process with kinetic constants k(1) = (0.03 +/- 0.01) h(-1) during the first 50 h and k(2) = (0.0037 +/- 0.0003) h(-1) for there up to 450 h. (C) 2003 Published by Elsevier Science B.V. [References: 23]