Melt Self-Assembly of Bottlebrush Block Copolymers

Bottlebrush block copolymers are comprised of densely grafted sidechains arranged in chemically distinct blocks along a linear polymer backbone. It is well known experimentally that bottlebrush block copolymers differ from their linear counterparts in the scaling of domain spacing with backbone length; we study this using both self-consistent field theory (SCFT) and fully fluctuating simulations (FTS). Using SCFT, we map the phase behavior for both symmetrical and asymmetrical arm bottlebrush block copolymers and observe a shifted order-disorder transition. We show that the shift in order-disorder transition in SCFT solely depends on a molecular architecture parameter. The SCFT results show conventional 2/3 scaling of domain size with backbone length, while FTS results to date hint at domain expansion. These studies were performed with varying chain statistics such as continuous Gaussian, discrete Gaussian, and freely-jointed chains; the particular choice having little impact on structure and phase behavior.