Single Helix Self-Assembled by Frustrated ABC(2) Branched Terpolymers
Single Helix Self-Assembled by Frustrated ABC(2) Branched Terpolymers
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受阻 ABC(2) 支化三元聚合物自组装单螺旋
DOI：
10.1021/acs.macromol.9b00110
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发表时间：
2019
期刊：
影响因子：
5.5
通讯作者：
Li Weihua
中科院分区：
文献类型：
--
作者：
Zhang Qi;Qiang Yicheng;Duan Chao;Li Weihua
具有 χACN≪ χABN∼ χBCN 受阻相互作用的线性 ABC 三嵌段共聚物可以自组装成双螺旋和三螺旋超结构，其中 B 嵌段形成螺旋域，包裹在 C 矩阵中的六边形堆积的 A 核心圆柱体周围。有人认为，B 螺旋和 A 圆柱体之间的长度比越大，往往会在每个圆柱体上形成更多数量的螺旋。在此基础上，我们提出对C嵌段进行支化，以扩大相对于A核心圆柱体的B螺旋域，从而降低长度比，即将线性ABC改为支化ABC2三元聚合物，旨在获得稳定的单螺旋超结构。对于一组典型的相互作用参数，χACN= 15 和 χABN= χBCN= 60，我们使用自洽场论构建了三角相图。在此相图中，单螺旋相 (H1C) 表现出显着的稳定区域。我们的计算表明，H1C的长度比仅略大于3，接近三缸叠缸上部结构（C3）的长度比。因此，C3 相占据了与 H1C 相邻的相当大的区域。事实上，我们发现单螺旋相相对于双螺旋或三螺旋相的稳定机制比基于长度比的定性论证复杂得多。尽管如此，我们的工作展示了一种通过定制 ABC 型嵌段三元共聚物的拓扑结构来调节螺旋数量的简便方法。
Linear ABC triblock copolymers with frustrated interactions of χACN≪ χABN∼ χBCNcan self-assemble into double- and triple-helical superstructures, where the B blocks form the helical domains wrapping around hexagonally packed A core cylinders in a C matrix. It has been argued that larger length ratio between the B helices and the A cylinder tends to form a larger number of helices on each cylinder. On the basis of this argument, we propose to branch the C block to enlarge the B helical domain relative to the A core cylinder and thus to reduce the length ratio, i.e., altering the linear ABC to branching ABC2terpolymer, aiming to obtain stable single-helical superstructure. For a typical group of interaction parameters, χACN= 15 and χABN= χBCN= 60, we construct the triangular phase diagram using self-consistent field theory. In this phase diagram, the single-helical phase (H1C) exhibits a notable stability region. Our calculations indicate that the length ratio of H1C is only slightly larger than 3, close to that of the triple cylinders-on-cylinder superstructure (C3). As a consequence, the C3phase occupies a considerable region neighboring to H1C. In fact, we find that the stabilization mechanism of the single-helical phase against the double-helical or triple-helical phase is far more complicated than the qualitative argument on the basis of the length ratio. Nevertheless, our work demonstrates a facile way to modulate the number of helices by tailoring the topological architecture of ABC-type block terpolymers.