(225b) Computational Studies of the Order-Disorder Transition in Block Copolymer Topological Blends

Block copolymer (BCP) based nanolithography provides an economical way to pattern nanoscale features for the semiconductor industry. Cyclization can reduce feature sizes, but like linear BCPs, cyclic BCP nanostructure size is still limited by the order-disorder transition (ODT). Although the ODTs of pure linear and cyclic BCPs have been studied extensively, there is little information on binary blends of these BCPs. We use dissipative particle dynamic simulations to study the impact of size mismatch and molecular architecture of component BCPs on the ODT for various blends. We see that the blend ODT always occurs at higher segregation strength than one would predict from linear interpolation of pure component ODTs. The deviation from this simple prediction is greater for blends with greater size mismatch between components. We find clustering of like components (linear with linear, cyclic with cyclic) in the disordered phase. Further, there exists a significant mismatch between the characteristic lengths associated with the component structures at the predicted segregation strength for blends with greater size mismatch between components. This results into the requirement of higher segregation strength to facilitate the cluster formations of comparable characteristic lengths for the transition to occur_.