Effect of sol-gel polymerization of tetraethylorthosilicate on internal aggregate structure in zinc-neutralized ethylene-methacrylic acid ionomers

Sol-gel reactions of tetraethylorthosilicate have been performed in three d ifferent zinc-neutralized ethylene-methacrylic acid copolymer ionomers for the purpose of creating nanostructured organic-inorganic materials with enh anced properties. Extended X-ray absorption fine structure (EXAFS) spectros copy was used to understand the effect of this in situ reaction on ionic ag gregate morphology. EXAFS spectra showed that no large changes occurred in the aggregate structure, indicating that the internal environment of the ag gregates did not nucleate the reaction, at least to the extent that the ion ic domains were significantly undisrupted. However, small changes in EXAFS patterns were evident. These changes could be a result of nucleation of the reaction at the edges of the aggregates, or aggregate size rearrangement c aused by the insertion of inorganic moieties into the polymer. However, the results indicate that the latter cannot include significant amounts of una ggregated zinc ions. (C) 2000 John Wiley & Sons, Inc.