Mössbauer spectroscopic study of sulphonated poly(ether-urethane) linear ionomer doped with iron species

Thermoplastic linear poly(ether-urethane) sulphonated ionomer (PEUSI), doped with natural Fe2+, was studied by Mössbauer spectroscopy at T = 78 and 290 K in order to monitor the chemical state of Fe species. The Fe2+ added was found to get only partly oxidised in the course of preparation of a dry polymer film from aqueous suspension. The oxidised part gave a ferric quadrupole doublet (over half of total Fe added) and, at T = 78 K only, a small portion of magnetically split sextet (ca. 3%), whereas FeII (total over 40%) stabilised in two different forms (represented by quadrupole doublets) corresponding to two types of iron(II) microenvironments, where FeII could be coordinated involving –CONH– and –NHNH– moieties and sulphonate groups in PEUSI. The results obtained show that Fe2+-doping of PEUSIbased materials may be used for probing their structural characteristics by Mössbauer spectroscopy.