(585d) Computational Studies of 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. Molecular 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 the 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, which we define as the excess segregation strength, is greater for blends with a greater size mismatch between components. We find that the blend components self-associate (linear with linear, cyclic with cyclic) in the disordered phase before the ODT. Further, the mismatch between the characteristic length scales of component clusters is positively correlated with the excess segregation strength at which the ODT occurs. These results suggest that cooperative chain rearrangements are necessary for the system to transition through the ODT, and that self-association of blend components hinders the transition.

*Funding Acknowledgements: NSF 1825881 (NSF CMMI); NSF 1852274 (NSF DMR REU)