PHYSICAL AND SPECTROSCOPIC STUDIES OF POLYPYRROLE FILMS CONTAINING TRANSITION-METAL EDTA CHELATES

Polypyrrole films containing transition-metal chelate counteranions, b ased on ethylenediaminetetraacetate (EDTA4-) and cyclohexanediaminetet raacetate (CDTA4-), have been prepared. The polymers (PPyMEDTA (M = Co , Cr, and Fe) and PPyMCDTA (M = Co and Fe)) have been characterized by elemental analysis, conductivity, X-ray diffraction, and TEM studies, as well as infrared, UV-visible, EPR, and Mossbauer spectroscopy. The conductivity of PPyFeEDTA and PPyCrEDTA initially increased upon expo sure to the environment and then stabilized, while that of PPyCoEDTA i nitially increased and then decreased very slowly; this behavior is su perior to that of the well-known p-toluenesulfonate system (PPyPTS). T he conductivity, degree of order, and conjugation length of the polyme rs were dependent upon the nature of the incorporated counteranion. TE M investigations of thin films of PPyCoEDTA revealed some crystallinit y, lattice fringes being observed. EPR spectroscopy showed that the co ordination of EDTA4- within the counteranion of PPyCrEDTA was sexadent ate. The low-temperature Mossbauer spectrum of PPyFeEDTA exhibited mag netic structure and indicated the presence of at least two counteranio n environments. In addition to an aggregated form, a large proportion of the counteranions is well dispersed within the polymer matrix.