EPR study of clustering in the poly(methacrylic acid)-copper(II) system

The reaction between poly(methacrylic acid) (PMAA) and Cu2+ ions was studie d at different ion concentrations and different degrees of neutralization o f carboxy groups. Three types of Cu2+ complexes were found to form in the P MAA-Cu2+ system: mononuclear tetragonal complexes; polynuclear associates ( clusters) with exchange interactions; and Cu2+ nitrate adsorbed on the PMAA surface. The limiting "capacity" for complexation is determined for the po lymer The neutralization of a solution of poly(methacrylic acid) with NaOH in the course of complexation with the Cu2+ ions gives rise to the structur al changes in the metal-containing polymer. At a low degree of neutralizati on (alpha = 0.1), the polynuclear clusters decompose to form Cu2+ dimers. E PR parameters of the Cu2+ dimer were determined by computer simulation.