writer：Dan Liu, Ying-Ying Wang, Ying-Chun Sun, Yuan-Yuan Han, Jie Cui, Wei Jiang
keywords：自组装, 四嵌段共聚物, 自洽场, 模拟, 相图
source：期刊
specific source：Chinese Journal of Polymer Science, 2018, 36(7), 888-896
Issue time：2018年

摘要：ABCA四嵌段共聚物为设计具有新颖结构的材料提供了新机会。本文采用实空间自洽场理论和模拟，系统研究了线性ABCA四嵌段共聚物在二维空间中的自组装行为，模拟在对称组成和对称相互作用条件下进行，重点关注A嵌段链长比以及A嵌段与B、C嵌段相互作用对共聚物自组装行为的影响。模拟结果表明，ABCA四嵌段共聚物自组装的大多数结构是中心对称的，如类两嵌段片层相、两种界面带珠片层相、两种分级片层相、六角蜂窝状相、含混合BC的片层相以及含混合BC的六角球状相。此外，当B、C嵌段间相互作用强时，可获得新颖的非中心对称Janus球；当B、C嵌段间相互作用弱时，可获得非中心对称片层相。通过比较候选有序结构的自由能，构建了不同B-C相互作用强度下ABCA四嵌段共聚物的相图。对体系亚稳态行为的研究表明，焓在ABCA四嵌段共聚物体系的亚稳态行为中起重要作用，可为实验中控制此类四嵌段共聚物结构提供有用指导。

Abstract：ABCA tetrablock copolymers offer new opportunities for design of materials with novel structures. Using real-space self-consistent field theory and simulation, we systematically examined the self-assembly behavior of linear ABCA tetrablock copolymers in a 2D space. The simulation was carried out under conditions of symmetrical compositions and interactions. We focus on the influence of chain length ratio of block A and interactions between block A and other blocks B and C on the self-assembly behavior of the copolymer system. The simulation results show that most of the structures self-assembled by the ABCA tetrablock copolymers are centrosymmetric, such as diblock-like lamella phase, two kinds of lamellae with beads at interface, two kinds of hierarchical lamella phase, hexagonal honeycomb-like phase, lamella phase with mixed BC and hexagonal spheres with mixed BC. Furthermore, we find that a novel noncentrosymmetric Janus spheres can be obtained when the interaction between blocks B and C is strong, whereas a noncentrosymmetric lamella phase was obtained at weak interaction between blocks B and C. Phase diagrams for the ABCA tetrablock copolymers with different interaction strength between blocks B and C are constructed by comparing free energies of candidate ordered structures. In addition, studies on the metastable behavior of the system reveal that enthalpy plays an important role in the metastable behavior of the ABCA tetrablock copolymer system, providing useful guide for structure control of such tetrablock copolymers in experiments.

论文链接：https://doi.org/10.1007/s10118-018-2106-y