Relative size of ionic aggregates determined by X-ray absorption spectroscopy

Extended X-ray absorption fine structure (EXAFS) spectra differed slightly with neutralization level in nominally dry ethylene-methacrylic acid copoly mer ionomers neutralized with zinc. These small changes in EXAFS spectra we re used to infer that decreases in average aggregate size occur with the de creasing neutralization level and that all zinc ions are in aggregates. How ever, at sufficiently low neutralization levels, EXAFS results indicate som e isolated zinc ions were also present. If no water is present, aggregates almost certainly terminate in zinc cations coordinated to two oxygen atoms from bidentate non-chelating carboxylate anions and two oxygen atoms from b identate chelating carboxylate anions. (C) 1999 Elsevier Science Ltd. All r ights reserved.