Anion clustering and fractal pattern growth in ion conducting polymeric matrix

Mobile iodine anions are shown to cluster in large size isotropic fractal patterns (Diffusion Limited Aggregates, DLA) in ion conducting polymeric system PEO:NaI (and also PEO:NH4I). Anisotropic ''tree-like'' patterns have also been obtained by deliberately creating physical interface such that the aggregating species arrive only from one direction. The aggregating species is I-3(-) which may thermally relax leading to the breaking up of the fractal arms. It is further shown that in the regions where I-2 (instead of I-3(-)) gets formed, a ''strain-field'' results forbidding further anion clustering.