Magnetic Property of Polymer-Rare Earth Complexes

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The objective is to prepare polymer complexes with rare earth ions in which a spin-spin interaction is expected between the polymer-bound ions and to study their magnetic property in connection with the matrix structure. Complexation of copolymer of methacrylic acid and acrylamide and of polyethyleneoxide-grafted polymethacrylic acid with rare earth ions such as Eu, Tb, and Sm was studied by potentiometric titration using modified Bjerrum's method. The copolymers formed the [rare earth ion (carboxylate)3] complex with large complex formation constants. Very large entropy change in the complexation contributed to the stable complex formation. The complexation was affected by distance between coordination sites and flexibility and hydration of the polymer chain. The complexes with the copolymers of methacrylic acid and acrylate gave transparent and flexible films. Visible absorption and fluorescent spectroscopy indicated that the rare earth ions formed the tris-coordinate complexes even in the films and the complexed ion were uniformly dispersed in the films. The Gd complex films showed paramagnetism. In order to improve the structure of polymer complexes, polypyridilenemethylidenenitrio and poly- <alpha> -pyrralenine were synthesized as polymer ligands with conjugated structure and were complexed with Eu, Gd, and Fe ion. The Gd complexes were paramagnetic. On the other hand, the corresponding Fe complexes showed strong ferromagnetism. Moessbauer parameters suggested that a trace ofiron oxides contaminated the polymer complexes and that the definite polymer matrices protectediron oxides as ultra fine particles in their domain. As mentioned above, new results to approach a polymeric magnetic substance were obtained by using the polymer-rare earth complexes.