Self-assembly of 21-arm star-like diblock copolymer in bulk and under cylindrical confinement.
Self-assembly of 21-arm star-like diblock copolymer in bulk and under cylindrical confinement.
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DOI：
10.1039/c4nr01275e
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发表时间：
2014-05
期刊：
影响因子：
6.7
通讯作者：
Yuci Xu;Weihua Li;F. Qiu;Zhiqun Lin
中科院分区：
文献类型：
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作者：
Yuci Xu;Weihua Li;F. Qiu;Zhiqun Lin
利用自洽平均场理论的伪谱方法探讨了 21 臂星形二嵌段共聚物在本体和约束下的相行为。通过比较不同结构的自由能构建了体积不对称相图。当星形二嵌段共聚物中的内部嵌段具有较小的体积分数时，发现螺旋相具有大的相区，这表明在这种条件下倾向于形成螺旋相。结合早期的实验工作，确定了多臂星形嵌段共聚物形成的片层周期D(multiarms)与臂数f相关的标度律，即D(multiarms)=D/f(1/2)，其中D是与星形二嵌段共聚物聚合度N相同的线性二嵌段共聚物的周期。标度定律也得到了标度理论的证实。星型二嵌段共聚物中形成的片层的桥联率接近100%，有利于提高其力学性能。在圆柱约束下产生了一些有趣的二维和三维形态，其中 3D 双螺旋被发现是最稳定的结构。
Phase behaviors of a 21-arm star-like diblock copolymer in bulk and under confinement were explored by using the pseudo-spectral method of a self-consistent mean field theory. An asymmetrical phase diagram in bulk was constructed by comparing the free energy of different structures. The gyroid phase was found to possess a large phase region when the inner block in the star-like diblock copolymer has a small volume fraction, suggesting the propensity to form the gyroid phase under this condition. Combined with the early experimental work, a scaling law correlating the period of lamellae D(multiarms) formed from multi-arm star-like block copolymers with the number of arms f was identified, that is, D(multiarms) = D/f(1/2), where D is the period of a linear diblock copolymer with the same degree of polymerization N as a star-like diblock copolymer. The scaling law was also substantiated by the scaling theory. The bridging fraction of the lamellae formed in a star-like diblock copolymer was nearly 100%, which is advantageous for improving its mechanical properties. Some interesting two-dimensional and three-dimensional morphologies were yielded under the cylindrical confinement, where a 3D double helix was found to be the most stable structure.