Spectroscopic studies on the incorporation of polypyrrole into zeolite channels

A composite film consisting of polypyrrole (PPy) and Y-type zeolite particles has been formed by electrolyzing pyrrole in aqueous suspension of Y-zeolite. It is indicated from the XRD pattern that the PPy in the composite is located within the channel of Y-zeolite, in which the cationic PPy is in combination with the negative surface of Y-zeolite. ESR spectrum of the composite film exhibited the resonance signal characteristic of conducting polymer in a partially oxidized (polaron) form. The optical intensity of this spectrum was considerably smaller than that of pure PPy. suggesting that a certain portion of PPy in the composite is stabilized by the formation of bipolarons (diamagnetic). During the electrochemical polarization of the PPy/Y-zeolite composite-electrode, PPy is found to remain undetached in the zeolite channel, and the charge to be balanced by incorporation and exclusion of electrolyte cations into/from the composite. (C) 2002 Elsevier Science B.V. All rights reserved.