Polymer blends are of great importance in the development of new polymeric materials. A usable polymer blend requires that the interfacial tension and interfacial adhesion in the blend be properly controlled, because of its role in governing the blend morphology and its associated mechanical properties. This can be achieved by adding to an immiscible polymer blend, appropriate interfacial agents (compatibilizers) like block and graft copolymers that locate preferentially at the interface. As a result, the interfacial tension is reduced.