Cai Dong, Li Jinbin, Ma Zhuang, Gan Zhanhui, Shao Yu, Xing Qian, Tan Rui, Dong Xue-Hui
South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
ACS Macro Lett. 2022 Apr 19;11(4):555-561. doi: 10.1021/acsmacrolett.1c00788. Epub 2022 Apr 5.
The inherent statistical heterogeneities associated with chain length, composition, and architecture of synthetic block copolymers compromise the quantitative interpretation of their self-assembly process. This study scrutinizes the contribution of molecular architecture on phase behaviors using discrete ABA triblock copolymers with precise chemical structure and uniform chain length. A group of discrete triblock copolymers with varying composition and symmetry were modularly synthesized through a combination of iterative growth methods and efficient coupling reactions. The symmetric ABA triblock copolymers self-assemble into long-range ordered structures with expanded domain spacings and enhanced phase stability, compared with the diblock counterparts snipped at the middle point. By tuning the relative chain length of two end blocks, the molecular asymmetry reduces the packing frustration, and thus increases the order-to-disorder transition temperature and enlarges the domain sizes. This study would serve as a quantitative model system to correlate the experimental observations with the theoretical assessments and to provide quantitative understandings for the relationship between molecular architecture and self-assembly.
合成嵌段共聚物的链长、组成和结构所固有的统计异质性，不利于对其自组装过程进行定量解释。本研究使用具有精确化学结构和均匀链长的离散ABA三嵌段共聚物，仔细研究了分子结构对相行为的影响。通过迭代生长方法和高效偶联反应相结合，模块化合成了一组具有不同组成和对称性的离散三嵌段共聚物。与在中点处截断的二嵌段共聚物相比，对称ABA三嵌段共聚物自组装成具有更大域间距和更高相稳定性的长程有序结构。通过调节两个端嵌段的相对链长，分子不对称性降低了堆积受挫，从而提高了有序-无序转变温度并扩大了域尺寸。本研究将作为一个定量模型系统，将实验观察结果与理论评估相关联，并为分子结构与自组装之间的关系提供定量理解。
