Reactive compatibilization

Reactive compatibilization is the process of modifying a mixed immiscible blend of polymers to arrest phase separation and allow for the formation of a stable, long-term continuous phase. It is done via the addition of a reactive polymer, miscible with one blend component and reactive towards functional groups on the second component, which result in the "in-situ" formation of block or grafted copolymers.

Source: Wikipedia — Reactive compatibilization (CC BY-SA 4.0)