Compatibilization of an immiscible polymer pair, poly(ethyl acrylate) and poly(ethylene terephthalate), was accomplished by incorporating vinylpyridine groups and zinc-neutralized sulfonate groups, respectively, along the polymer chains. The compatibility of this multiphase ionomeric blend resulted from the formation of a zinc-pyridine-sulfonate group coordination complex between polymer chains. The nature and degree of this complexation were successfully probed with FTIR spectroscopy. Two blend compositions with one containing a stoichiometric amount of the interacting groups were prepared. The degree of compatibility was established with DSC and DMTA. It was found that the level of mixing depended upon the extent of specific interactions between the polymer chains. In addition, interesting phase behavior of the blends was discovered by DMTA. Results showed that upon crystallization the PET-SO3Zn-rich phase in both ionomeric blends exhibited an increase in the temperature of the loss peak associated with segmental motions accompanying T(g), while the EAV-P-rich phase showed a decrease in the temperature of its corresponding loss peak.