Improved toughness of incompatible polymer mixtures via sequence-defined compatibilizers

Compatibilizers can be used as part of a broader strategy to upcycle incompatible plastic mixtures. Recent experiments demonstrate that using tetrablock copolymers as compatibilizers increases the toughness of incompatible polymer blends significantly, while using diblock copolymers does not. This observation leads to the question: how does the compatibilizer sequence determine the toughness of incompatible polymer mixtures? Here, we examine this question through the use of coarse-grain molecular dynamics simulations in which we add various sequence-defined copolymer compatibilizers to an incompatible polymer blend. Analogously to experiments, we equilibrate these systems in the melt, cool well below the glass transition temperature, and strain them until failure. We seek to understand how sequence affects structure at the interface and how this leads to enhanced toughness of the polymer blend.