FT-IR-ATR SPECTROSCOPIC STUDY OF THE SPONTANEOUS POLYMERIZATION OF PYRROLE IN IRON-EXCHANGED MONTMORILLONITE

The oxidative polymerization of pyrrole in montmorillonite clay is fol lowed in real time using in situ FT-IR-ATR spectroscopy. A conducting polymer-clay composite is formed as the ferric sites present at the ac cessible surfaces of the clay particles chemically oxidize the aromati c heterocycle. The infrared spectra indicate that the conducting polym er formed resembles electrochemically prepared polypyrrole and that, d ue to mass transport control of the reaction, no evidence of overoxida tion of the pyrrole ring is found. No IR-evident changes are found for the aluminosilicate structure of the clay mineral. From analysis of t he change in pyrrole concentration it can be determined that the overa ll process consists of three steps: pre-concentration, polymerization and pyrrole diffusion. By comparing diffusion limited data for experim ents performed with and without the clay layer a relative measure of t he diffusion coefficient for pyrrole in the composite is obtained.