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Modern Physics 2022
AB型嵌段共聚物在薄膜受限下形成穿孔层结构的理论研究
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Abstract:
采用自洽场理论方法研究了平行板受限下AB型嵌段共聚物的分子链拓扑结构对自组装行为的影响。首先设计了AmB多臂星型嵌段共聚物，研究臂数m对穿孔结构(PL)稳定性的影响，通过构建m = 1，2和4关于A组分的体积分数(fA)和受限尺寸(D)的相图，发现臂数m的增加有利于拓宽PL结构在fA上的稳定区间；但当m > 2时，区间增加的不是很明显。然后固定m = 2，通过改变其中一个A嵌段在B嵌段上的连接位置，用参数τ来调控，即设计ABAT型嵌段共聚物，来研究τ对PL结构稳定性的影响。通过构建0 < τ ≤ 1时关于fA~D的相图，得出有利于PL结构稳定的τ值，并通过分析不同τ时PL结构的自由能贡献、链段分布和结构特征尺寸等的变化规律，得出A嵌段的自由度受其在B嵌段上的连接点位置的影响，其在相畴中的空间分布直接影响到PL结构的稳定性。该研究为相关实验上制备穿孔结构提供理论指导。
The effect of chain topology on the self-assembly behavior of AB-type block copolymers confined in thin film was studied using the self-consistent field theory method (SCFT). Firstly, the AmB miktoarm star copolymer was designed and the effect of the number of arms m on the stability of per-forated lamella (PL) structure was investigated by constructing the phase diagrams for m = 1, 2 and 4 with the volume fraction (fA) and size of confinement (D). The increasing m is beneficial to expanding the stable phase region of the PL structure, while it increases not very obviously when m > 2. Then fix m = 2 and the ABAT-type block copolymer was designed by regulating the tethering point of one A block on the B block, which is characterized by the parameter τ. The favorable τ for the stability of the PL phase is examined by constructed the phase diagram of fA~D, where the free energy contributions, segment distribution and feature size of the PL structure under different τ are analyzed. It indicates that the degree of freedom of the A block is affected by the tethering point on the B block, and its spatial distribution in the domain affects the stability of the PL structure. This study provides theoretical guidance for the preparation of perforated structures in related experiments.
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