Stability of the Double Gyroid Phase in Bottlebrush Diblock Copolymer Melts

Bottlebrush block copolymers are emerging as promising materials for designing advanced materials with a number of unique properties engendered by densely grafted architectures. We used self-consistent field theory (SCFT) to determine how the stability of the double gyroid phase in a diblock copolymer melt is affected by converting one or both of the blocks of a linear diblock copolymer to a bottlebrush architecture. For architecturally symmetric polymers, the dominant effect of the bottlebrush is increasing segregation strength, whereupon the gyroid stability regions are effectively the same as linear diblock copolymers at equivalent segregation. In contrast, architectural asymmetry produced by coil–bottlebrush block polymers significantly impacts the gyroid stability region as a result of conformational asymmetry, which promotes spontaneous curvature. Gyroid is more stable when the coil blocks are in minority domains, which relieves packing frustration at the center of the gyroid nodes than in majority domains. Our results suggest that architectural asymmetry in bottlebrush block polymers can be a powerful design tool.