Xu Yuci, Li Weihua, Qiu Feng, Lin Zhiqun
Department of Macromolecular Science and Engineering, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China.
Nanoscale. 2014 Jun 21;6(12):6844-52. doi: 10.1039/c4nr01275e.
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.
采用自洽平均场理论的伪谱方法，研究了一种21臂星状二嵌段共聚物在本体和受限条件下的相行为。通过比较不同结构的自由能，构建了本体中的非对称相图。当星状二嵌段共聚物中的内嵌段体积分数较小时，发现螺旋状相具有较大的相区，这表明在这种条件下倾向于形成螺旋状相。结合早期的实验工作，确定了一个标度律，该标度律将多臂星状嵌段共聚物形成的片层周期D（多臂）与臂数f相关联，即D（多臂）=D/f(1/2)，其中D是与星状二嵌段共聚物具有相同聚合度N的线性二嵌段共聚物的周期。标度理论也证实了该标度律。星状二嵌段共聚物中形成的片层的桥接分数接近100%，这有利于改善其机械性能。在圆柱形受限条件下产生了一些有趣的二维和三维形态，其中发现三维双螺旋是最稳定的结构。
