AbstractThe preparation, rheology, and mechanical properties of a family of blends composed of transition‐metal neutralized sulfonated ethylene‐propylene‐diene elastomers (S‐EPDM) and styrene‐4 vinylpyridine copolymers (SVP) are described. These polymeric materials contain relatively low levels of interacting groups (≤ 10 mol%), which are, however, sufficient for forming an intermolecular complex. A distinguishing characteristic of these blends is that the rheology and mechanical properties are strongly influenced by a coordination‐type bonding between the transition metal and the basic nitrogen unit. As a result, markedly improved and enhanced physical properties are observed, especially when the stoichometric ratio of the interacting moieties are approached (SO/N = 1/1). This enhancement in properties is clearly exhibited in melt viscosity data, dynamic mechanical data, and thermal data. The blend morphology is also altered by complex formation, as is observed in scanning electron microscopy of the blends from which one of the ingredients was selectively extracted. At the stoichometric ratio, the blend of the olefinic elastomeric ionomer and the styrenic thermoplastic copolymer approaches a single‐phase system. Such blends are otherwise completely immiscible when the coordination‐type interacting groups are absent from either of the individual components. Accordingly, it was observed that nontransition‐type (Na, Mg) counterions have only a marginal effect on the compatibility of these blends, as is the case in the completely unfunctionized blend components.