Scattering ionic, maximum

Fujimura M., Hashimoto T., and Kawai H., Small-angle x-ray scattering study of perfluorinated ionomer membranes. 2. Models for ionic scattering maximum. Macromolecules, 15, 136, 1982. 

Figure 2. Two morphological models used to describe the origin of the ionic SAXS maximum observed for Nafion (a) the modified hard-sphere model depicting interparticle scattering and (b) the depleted-zone core—shell model depicting intraparticle scattering. (Adapted with permission from ref 36. Copyright 1981 American Chemical Society.)...

PAMAM dendrimer in methanol[19], and larger also than the 60 A maximum physical radius of a completely stretched structure, but has been employed consistently. In terms of the model, some of the scatter in Figure 4 can be explained by considering that the radius of gyration of this polyelectrolyte is likely to depend on the ionic strength, pH, and even the concentration of borate diesters (internal cycles) none of these factors were systematically controlled in this study. 

Several publications report electrokinetic curves with maxima or minima of the potential (beyond the scatter of data points) but without multiple lEPs. A minimum (maximum in absolute value) in the basic range is reported in all systems but one studied in [225], in [476], and in [266,477] (silica, with various KCl concentrations). A maximum in the potential of FeOOH at pH = 4.5 was found in [478]. These maxima or minima may be caused by an increase in ionic strength when the dispersion is adjusted to very high or very low pH. 

In our earlier papers 04, 11) the ionic scattering maximum is proposed to arise from the ionic clusters(9) which are essentially ion-rich regions containing some fluorocarbon chains. The clusters are stabilized by the dipole-dipole interaction between the... 

Figure 8. Two models describing the spatial organization of the ionic sites, a Two-phase model composed of ionic clusters (ion-rich regions) dispersed in a matrix of the intermediate ionic phase, which is composed of fluorocarbon chains and nonclustered ions. The ionic scattering maximum arises from an interparticle interference effect, reflecting an average intercluster distance S. b Core-shell model in which the ion-rich core is surrounded by an ion-poor shell composed mostly of perfluorocarbon chains. The core-shell particles are dispersed in the intermediate ionic phase. The scattering maximum arises from an interparticle interference effect, reflecting a short-range order distance S of the core-shell particle. Note that the crystalline region was not drawn in the model for the sake of simplification and that the shape of the core-shell particle may not necessarily be spherical.

---