Exploration of complex nanostructures in block copolymer*

The exploration of three-dimensional (3D) nanostructures in block copolymers involves the manipulation of compositional fluctuations at interfaces, induction of conformational asymmetry, and design of complex architectures. Despite the abundance of such nanostructures identified to date (e.g., triply periodic minimal surfaces and Frank–Kasper phases), the experimental demonstration of thermodynamically stable complex 3D structures with high packing frustration remains limited. In this talk, I would like to show the importance of molecular interactions for stabilizing complex 3D structures and proposes the use of end-group chemistry as a versatile method for realizing thermodynamically stable network structures with high packing frustration in simple linear diblock copolymers. I advocate revising conventional block-copolymer phase diagrams to consider end–end interactions and end-group arrangements. In instances where end-functionalized block copolymers exhibit strong end–end interactions, the lam structures are confined to a narrower phase diagram window. Conversely, a broader phase window enables the stabilization of diverse network structures such as gyroid, diamond, and primitive phases. This approach can reveal unprecedented network structures in various soft materials.