Pentablock Copolymer Design-Morphology-Chain Conformation Relationship Studied by Self-Consistent Field Theory and Molecular Dynamics Simulation

Block copolymer (BCP) self-assembled nanostructures have applications in electronics, optics, separations, and photonics. Tailoring the BCP design has been a strategy for targeting desired nanostructures for each application, but the large number of BCP design parameters makes it challenging to explore purely through experiments. To complement experiments, Self-consistent field theory (SCFT) has been used successfully to predict morphological phase diagrams of BCPs for varying sequences, compositions, and architecture. However, due to the mean field approximation, SCFT has limitation in providing explicit chain conformations, which are required to understand molecular arrangements and driving forces for the observed phase behavior. We overcome this challenge with SCFT by combining SCFT calculations with particle-based molecular dynamics (MD) simulations which provide explicit chain conformations. SCFT enables rapid screening of BCP design space to identify the design rules for desired morphologies, and coarse-grained MD simulations elucidate distributions of chain conformations within each SCFT-predicted equilibrium morphology. Using this combined SCFT-MD approach, we investigate the phase behavior of pentablock copolymers for varying composition, block sizes, segregation strength, and statistical segment length ratio.