MOSSBAUER-SPECTROSCOPY OF FE-2+-COMPLEXED POLY(N-PROPYLPYRROLE-SULFONATE)

The polymer obtained by chemical oxidation of N-propylpyrrole-sulfonate (PPS) with Fe(ClO//4)//3 is studied through elemental analysis and Moessbauer spectroscopy. From elemental analysis data this polymer appears to be composed of a polypyrrolic backbone with side chains of alkylsulfonate pendant groups. These sulfonate groups are mainly in the form of iron salts that act as a dopant of the poly(PPS). Moessbauer spectra of iron-complexed poly(PPS) has been analyzed as functions of temperature, water content, and applied magnetic field in order to characterize the iron environment. Nearly 95% of the iron ions are ferrous ions in different environments. The spectra of a dried sample or a fully hydrated one, which are recorded at a given temperature, were fitted by using identical isomer-shift values but two different distributions or quadrupole doublets (the Q. S. evolution with temperature was the same). The Debye temperature of the two samples has the same value, but the recoil-free fraction falls to zero somewhere above 340 K for a dried sample and near 290 K for the fully hydrated material.