Shi Jiahao, Huang Xianbo, Li Weihua
State Key Laboratory of Molecular Engineering of Polymers, Key Laboratory of Computational Physical Sciences, Department of Macromolecular Science, Fudan University, Shanghai 200433, China.
National-certified Enterprise Technology Center, Kingfa Science and Technology Co., Ltd, Science City, Guangzhou 510663, China.
Phys Chem Chem Phys. 2023 Jul 26;25(29):20032-20041. doi: 10.1039/d3cp00994g.
The self-assembly behaviors of AB miktoarm star copolymers as one typical type of asymmetric architecture have been studied well in the past few decades due to their deflected phase boundaries. In particular, recently, they have attracted renewed theoretical interest due to their expanded spherical phase region that stabilizes complex Frank-Kasper spherical phases. However, previous theoretical studies have never considered AB copolymers with unequal arm lengths, which is more or less the case for synthesized copolymers. In this work, we investigate the self-assembly behaviors of AB miktoarm star copolymers with unequal B-arms using self-consistent field theory. We propose an intramolecular polydispersity index () to quantify the distribution of unequal B-blocks. Accordingly, we further propose a simple quantity of an effective arm number = / for quantitatively comparing the phase boundaries between various AB copolymer samples with different arm numbers or different distributions of B-blocks. Our results indicate that different AB copolymers with equal exhibit similar phase diagrams. On the other hand, we also found that the phase boundaries of two different samples with same are not exactly overlapped. We speculate that the effect of spontaneous curvature may be mainly controlled by , but the packing frustration of B-blocks may also be dependent on the other quantities that are closely related to the shape of the distribution of B-arms, such as higher order polydispersity indexes.
AB型多臂星型共聚物作为一种典型的不对称结构，由于其偏离的相界，在过去几十年中得到了深入研究。特别是近年来，由于其扩展的球形相区域能稳定复杂的Frank-Kasper球形相，它们引起了新的理论关注。然而，以往的理论研究从未考虑过臂长不相等的AB共聚物，而合成共聚物或多或少存在这种情况。在这项工作中，我们使用自洽场理论研究了B臂长度不相等的AB型多臂星型共聚物的自组装行为。我们提出了一个分子内多分散指数（）来量化不相等B嵌段的分布。相应地，我们进一步提出了一个简单的有效臂数= / 的量，用于定量比较不同臂数或不同B嵌段分布的各种AB共聚物样品之间的相界。我们的结果表明，具有相同的不同AB共聚物表现出相似的相图。另一方面，我们还发现具有相同的两个不同样品的相界并不完全重叠。我们推测，自发曲率的影响可能主要由控制，但B嵌段的堆积挫折也可能取决于与B臂分布形状密切相关的其他量，如高阶多分散指数。
