Target-Directed Design of Phase Transition Path for Complex Structures of Rod-Coil Block Copolymers
Target-Directed Design of Phase Transition Path for Complex Structures of Rod-Coil Block Copolymers
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棒-线圈嵌段共聚物复杂结构相变路径的定向设计
DOI：
10.1021/acsomega.9b02984
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发表时间：
2019
期刊：
影响因子：
4.1
通讯作者：
Tang Ping
中科院分区：
文献类型：
--
作者：
Shao Jingyu;Jiang Nuofei;Zhang Hongdong;Yang Yuliang;Tang Ping
我们将弦方法应用于棒-线圈嵌段共聚体系的自洽平均场理论框架中，计算了在一定的外延生长关系下不同取向的片层和柱体在重排跃迁中的最小能量路径。与初始相相比，出现在重排序转变路径中的亚稳相倾向于在有序-有序转变边界的低χ侧形成结构。特别是，对于复杂的网络，亚稳态相，如单一的回旋体和穿孔的片层，需要在有序-无序转变边界附近的片层或圆柱体之间选择一个重排转变，它们的外延生长关系相同，但取向不同。这一通过合理设计相图中特定相间重排转变来获得复杂亚稳态相的策略，不仅适用于广泛的χ网络体系，也适用于线圈-线圈嵌段共聚体系。结合自由能、熵、不同块体间的混合度和棒在相变过程中的平均取向度的贡献分析，进一步研究了重排相变行为。基于这一机理，我们开发了一种目标导向的设计策略来构建自组装的棒-线圈嵌段共聚物的亚稳态结构。
We apply the string method to the self-consistent mean-field theory framework of the rod–coil block copolymer system to calculate the minimum energy pathways in the rearrangement transitions of lamellae and cylinders with different orientations under certain epitaxial growth relationship. Metastable phases appearing in the reordering transition pathway tend to form the structure at low χNside of the order–order transition boundary compared with the initial phase. In particular, for complex network, metastable phases, such as single gyroid and perforated lamellae, need to select a rearrangement transition between lamellae or cylinders near the order–disorder transition boundary with the same epitaxial growth relationship but different orientations. It is confirmed that this strategy for obtaining complex metastable phases by rational design of rearrangement transition between specific phases in the phase diagram can be applied to a wide range of χNas well as the coil–coil block copolymer system. We further investigate the rearrangement transition behavior combining with the analysis of contribution from the free energy, entropy, degree of mixing between different blocks, and the average orientation degree of rods during the phase transitions. Based on this mechanism, we have developed a target-directed design strategy for constructing self-assembled metastable structures of rod–coil block copolymers.