The supramolecular microstructure of ionomers
Polimery 1997, No 6, 353
Several modeling concepts on the aggregation microstructure of ionomers were reviewed, including (i) the para crystalline network model, (ii) Yarusso—Cooper's hard-sphere model, and (iii) core—shellmodels. Ion groups are postulated to exist in the form of multiplets and clusters. The former are tight aggregates of some ion pairs, the latter (ion-richphases) are aggregations of many multiplets forming domains (5—10 nm in diam.) that, in addition to ions, contain hydrocarbon units. A common feature of models (i) and (ii) is that the ionomer peak (a broad maximum centered at (4 π /λ ) зт Ф = 0 .5—5 nm-1, where 2Ф = scattering angle, λ = X-ray wave length) is ascribed to interferences between individual ion aggregates. In model (iii), this peak is attributed to interferences associated with ion aggregate's structure. Arguments in favor and disfavor of each model resulted in (iv) Eisenberg's multiplet—cluster model which, together with (ii), describes best the ionomer structure.