A spin‐probing study of non‐magnetic ionomers: Cu²⁺ ‐containing polyethylene/methacrylic acid copolymer neutralized with Zn²⁺

Abstract

SUMMARYA spin-probing technique was first applied to a study of a non-magnetic ionomer, polyethylene/methacrylic acid copolymer neutralized with Zn2+ (E-MAA-Zn); 2 mol-Vo Cu2+ ions were incorporated in replacement of Zn2+, and its ESR spectra were observed in detail at various temperatures in order to obtain physico-chemical properties of E-MAA-Zn, especially its structural changes. We found no significant influence of the 2 mol-Vo Cu2+-incorporation upon the properties of the Zn2+ ionomer by differential scanning calorimetry (DSC), which showed two endothermic peaks, 1) an irreversible one at lower temperature which is associated with the ionic aggregate phase in the ionomer, 2) a reversible one at higher temperature with considerable thermal hysteresis which is due to melting of the polymer main chains. ESR hyperfine coupling constants (A and A I) of Cu2+ showed no sign of structural changes of the polymer around the phase-transition temperatures, whereas ESR g-values (sll and g I) of Cu2+ proved the onset of the softening of the polymers to be attributable to polymer melting. The latter slope-changes in the temperature dependences were reversible, although with considerable thermal hysteresis. These findings are compatible with the DSC data. As for the irreversibility regarding the endotherm at lower temperature, broad ESR hyperfine components recovered gradually, indicating an order-disorder nature of the ionic aggregate phase transition.

Infrared Spectroscopic Study of the Binary Blends of Sodium and Zinc Salt Ionomers Produced from Poly(ethylene-co-methacrylic acid)

“…The IR studies have provided microscopic information about how the ionic aggregates are formed and how the formation results in the improvement in performance. We are now exploring other combinations of the neutralizing cations in EMAA ionomers to design the desired ionomer properties, where IR spectroscopy will be useful for the characterization, but as commented, it is also necessary to use the aid of other experimental techniques, such as EXAFS, XANES, and ESR, , for better understanding.…”

Kinetics study on melt grafting copolymerization of LLDPE with acid monomers using reactive extrusion method

“…Propagation free radical of AA exhibits the 9-line ESR signals, which are observed in acrylate polymerization at high monomer conversion. 33 The ESR spectrum of MMA is similar to that of AA, but it is not as obvious as AA. The time evolution of concentration of propagation free radical [M i ⅐] is shown in Figure 7.…”

Self-Assembling of Ethylene−Methacrylic Acid Ionomers in Aqueous Solutions and as Swollen Membranes, from ESR Spectra of Amphiphilic Spin Probes. 1. Structure of Aggregates and Effect of Ionomer Concentration

“…The poly(ethylene- co -methacrylic acid) (EMAA) ionomers, Chart 1a, were one of the first ionomers to be studied, ,,− and the term “ionomer” was used in this system for the first time. , SAXS studies in partially or fully neutralized EMAA ionomers have revealed a new peak that became known as the “ionic peak” and is still considered diagnostic for microphase separation in ionomers. The ionic peak has been assigned to scattering from ordered hydrocarbon chains between the ionic aggregates .…”