Most processed polymer mixes consist of a dispersed phase in a more continuous matrix of the other component. The formation, size, and concentration of this disperse phase are typically optimized for specific mechanical properties. If the morphology is not stabilized, the dispersed phase may coalesce under heat or stress from the environment or further processing. This coalescence may result in diminished properties (brittleness and discoloration) due to the induced phase separation. These morphologies can be stabilized by sufficient interfacial adhesion or lowered interfacial tension between the two phases.
A common technique involves functionalizing one monomer. For example, Nylon-rubber bands are polymerized with functionalized rubber to produce graft or block copolymers. The added structures make it no longer favorable to coalesce and/or increase the steric hindrance in the interfacial area where phase separation would occur.