Phase separation in block copolymers and the plethora of patterns 

Merin Joseph, Post-Doctoral Researcher, Niels Bohr Institute, University of Copenhagen, Denmark

Block copolymers, composed of two or more chemically distinct monomer species, undergo mesoscopic phase separation, leading to the formation of diverse self-assembled structures. The resulting morphologies are governed by the monomer composition, chemical incompatibility, molecular architecture, and rigidity of different blocks.

In diblock copolymers, phase separation can give rise to structures ranging from disordered, liquid-like domains to highly ordered bicontinuous phases.  When compositional, conformational, or interactional symmetry is broken,  these systems favor the emergence of lower-symmetry phases, including complex Frank-Kasper structures, networks, and quasi

crystals. The formation of these morphologies is driven by the interplay between interfacial tension and block stretching, which together minimize the free energy of the system. 

The stability of these structures can be studied using different mathematical frameworks: mean-field theories, molecular dynamics, and density functional theory. We can also combine information from pattern formation to understand these structures. 

In this talk, I will provide an overview of block copolymer phase separation and elaborate on the different methods with which these structures are studied focusing on a specific block copolymer architecture known as  ABC miktoarm.

References:

[1]. Frank S. Bates, Glenn H. Fredrickson; Block Copolymers—Designer Soft Materials. Physics Today 1 February 1999; 52 (2): 32–38

[2]. Kevin D. Dorfman; Computational Phase Discovery in Block Polymers. ACS Macro Lett. 2024, 13, 12, 1612–1619

[3]. Joseph M, Read D.J, Rucklidge A.M, Design of Linear Block Copolymers and ABC Star Terpolymers That Produce Two Length Scales at Phase Separation, Macromolecules 2023, 56, 19, 7847–7859