Topology Effect on Order–Disorder Transition of High-χ Block Copolymers
Cheng-Yen Chang, Gkreti-Maria Manesi, Jiayu Xie, An‐Chang Shi, Thanmayee Shastry, Apostolos Avgeropoulos, Rong‐Ming Ho
Abstract
High Resolution Image Download MS PowerPoint Slide This work aims to systematically examine the topology effect on the self-assembly of block copolymers. Compositionally, symmetric polystyrene- block -polydimethylsiloxane block copolymers (BCPs) with different chain topologies (diblock, three-arm star-block, and four-arm star-block) and various molecular weights are synthesized. These purposely designed block copolymers are used as a model system to investigate the topology effect on order-to-disorder transition temperature ( T ODT ) by temperature-resolved small-angle X-ray scattering experiments. An increase of the T ODT is observed when the arm number of BCPs with equivalent arm length (i.e., molecular weight) is increased from one to four. Based on the random-phase approximation (RPA), Flory–Huggins interaction parameter (χ) is determined from the regression of the measured T ODT . The observation by differential scanning calorimetry also demonstrates the shifting of the endothermic peak from the order-to-disorder transition of star-blocks to the higher temperature region, consistent with the scattering experiments and the RPA prediction.