STRUCTURE AND PROPERTIES OF THE NEODYMIUM(III) SALTS OF POLY(ETHYLENE-CO-METHACRYLIC ACID)

Neodymium(III) (Nd(III)) salts of poly(ethylene-co-5.4 mol% methacryli c acid) (EMAA) were synthesized in the neutralization range from 0 to 100%. The coordination structure, the formation and structure of ionic aggregates and their microphase separation were investigated. The inf rared spectral results suggested that local environments around Nd(III ) ions significantly change near 50% neutralization. Above this degree of neutralization, the X-ray scattering and visible spectral results indicated the presence of ionic aggregates. Interestingly, almost simu ltaneously with the ionic aggregation, a microphase separation of ioni c aggregates from the polymer matrix (the formation of ionic cluster p hase in Eisenberg's terminology) was found to take place by dynamic me chanical and dielectric relaxational measurements. The activation ener gy for the a relaxation (340-420 kJ mol(-1)), which is attributed to t he glass transition of the ionic cluster phase, and the melt flow rate revealed that the Nd(III) ionomers were densely cross-linked by eithe r isolated or aggregated ions. The stiffness also indicated the existe nce of the densely cross-links, and the Nd(III) ionomers exhibited the higher stiffness compared with the monovalent and divalent salts of E MAA.