The architecture of a block copolymer plays a pivotal role in tailoring its self-assembly behavior. In this work, discrete AB₂ linear–branched block copolymer isomers with identical chemical structures but varying molecular symmetry were prepared and studied. Comparing to AB linear diblock copolymers, linear–branched AB₂ counterparts exhibit significantly different assembly behaviors, which can be further regulated by adjusting the relative chain length of two B branches. A minor difference in the chain lengths of the B blocks results in an expansion in domain sizes and enhanced phase stability, while a larger asymmetry triggers phase transitions from a cylindrical structure to various spherical phases. The synergistic effects of the long and short B blocks effectively alleviate packing frustration, leading to a nonmonotonic deflection of the spherical/cylindrical phase boundary. The unique phase behaviors were substantiated by a self-consistent field theory study. This work demonstrates the feasibility and robustness of tailoring assembly behaviors by rational manipulation of chain architecture, providing insights into the underlying mechanism that stabilizes unconventional spherical phases.

中文翻译：

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分子对称性对 AB2 线性支链嵌段共聚物自组装行为的影响


嵌段共聚物的结构在定制其自组装行为方面起着关键作用。在这项工作中，制备并研究了具有相同化学结构但分子对称性不同的离散 AB₂ 线性支链嵌段共聚物异构体。与 AB 线性二嵌段共聚物相比，线性支链 AB₂ 对应物表现出明显不同的组装行为，这可以通过调整两个 B 支链的相对链长来进一步调节。B 嵌段链长的微小差异导致畴大小的扩大和相稳定性的增强，而较大的不对称性会触发从圆柱形结构到各种球形相的相变。长 B 块和短 B 块的协同效应有效地缓解了填充挫折，导致球形/圆柱形相边界的非单调偏转。独特的相位行为被自洽场论研究证实。这项工作证明了通过合理操纵链架构来定制组装行为的可行性和稳健性，为稳定非常规球形相位的底层机制提供了见解。