Self-consistent field theory study of self-assembly of bottlebrush diblock copolymers*

Bottlebrush block copolymers are characterized by densely grafted side chains onto a long polymeric backbone, and this feature enables unique self-assembly properties which are hard to achieve with conventional diblock copolymers. Recent advances of molecular synthesis techniques and designing lamella forming bottlebrush polymers for photonic crystals have led to interests in bottlebrush molecular design for achieving advanced network nanostructure materials. In this talk, we present our recent study on the self-assembly behaviors of bottlebrush diblock copolymers using self-consistent field theory, focusing on the stability of the double gyroid phase in various bottlebrush architectures including coil-bottlebrush copolymers. We found that the dominant effect of increasing side chain length in the architecturally symmetric bottlebrush copolymers is increasing segregation strength by adding segment volumes on the backbones, and the gyroid regions of the phase diagram are almost identical to linear diblock copolymers at equivalent segregation. In contrast, architecturally asymmetric coil-bottlebrush copolymers significantly deflect the gyroid region due to the conformational asymmetry, promoting the spontaneous curvature toward the coil block.