Entanglements in block copolymers self-assembled into lamellae morphology

Understand the viscoelastic behavior of polymers is of fundamental interest but also is relevant to consider their technological applications. It is well-known that the mechanical properties of polymers depend fundamentally on the molecular chain weight. The main effect of increasing weight is the arise of entanglements.
Entanglements in homopolymer systems have been studied through simulations and experiments and supported by theories. However, little is known about those topological constraints on multi-component systems, like the block copolymers (BCPs).
In this work, we investigate the viscoelastic properties of BCPs when segregating in a lamellar morphology. We found the entanglements are not distributed homogeneously in the space but instead follow the underlying pattern of the segregated domains. Moreover, the interface separating nearby domains induces a surface effect, decreasing the number of entanglement. On the other hand, in the center of the lamellae domain, the monomer density slightly increases due to the impact of the attractive potential, whose main consequence is an increment of the number of entanglements. Both results are locals, compete with each other, and depend on the segregation regime, being more extended in space in the regime of strong segregation.