Mössbauer spectroscopic study of the temperature dependence of the intramolecular mobility of a cross-linked polymeric cation-exchanger based on acrylic acid

The temperature transition of a solvated cross-linked polymer (the SGK-7 carboxyl cation-exchanger, which contains iron(III) ions) from the solid state to a state characterized by intense intramolecular motions was detected and studied by Mossbauer spectroscopy. Triggering of two types of motions was demonstrated: high-frequency vibrations of atoms with a higher amplitude (manifested by a sharp decrease in the probability of the Mossbauer effect) and slower (conformational) motions (manifested by a change in the shape of the spectrum). The parameters of the motions were determined within the framework of the lattice model and the effect of the solvating liquid on the nature of the transition was demonstrated.