The phase behavior of binary blends composed of A${}_1$B${}_1$ and A${}_2$B${}_2$ diblock copolymers is systematically studied using the polymeric self-consistent field theory, focusing on the formation and relative stability of various spherical packing phases. The results are summarized in a set of phase diagrams covering a large phase space of the system. Besides the commonly observed body-centered-cubic phase, complex spherical packing phases including the Frank–Kasper A15, $\sigma$ and the Laves C14, C15 phases could be stabilized by the addition of longer A${}_2$B${}_2$-copolymers to asymmetric A${}_1$B${}_1$-copolymers. Stabilizing the complex spherical packing phases requires that the added A${}_2$B${}_2$-copolymers have a longer A-block and an overall chain length at least comparable to the host copolymer chains. A detailed analysis of the block distributions reveals the existence of inter- and intra-domain segregation of different copolymers, which depends sensitively on the copolymer length ratio and composition. The predicted phase behaviours of the A${}_1$B${}_1$/A${}_2$B${}_2$ diblock copolymer blends are in good agreement with previous experimental and theoretical results. The study demonstrates that binary blends of diblock copolymers provide an efficient route to regulate the emergence and stability of complex spherical packing phases.

中文翻译：

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二嵌段共聚物的二元共混物：复杂球形堆积相的有效途径

由 A 组成的二元混合物的相行为${}_1$乙${}_1$ 和A${}_2$乙${}_2$使用聚合物自洽场理论系统地研究了二嵌段共聚物，重点是各种球形堆积相的形成和相对稳定性。结果汇总在一组相图中，涵盖了系统的大相空间。除了常见的体心立方相，复杂的球形堆积相，包括 Frank-Kasper A15，$\sigma$ Laves C14、C15 相可以通过添加更长的 A 来稳定${}_2$乙${}_2$-不对称A的共聚物${}_1$乙${}_1$-共聚物。稳定复杂的球形堆积相需要添加的 A${}_2$乙${}_2$-共聚物具有更长的A-嵌段和至少与主体共聚物链相当的总链长。对嵌段分布的详细分析揭示了不同共聚物的域间和域内分离的存在，这敏感地取决于共聚物长度比和组成。A 的预测相行为${}_1$乙${}_1$/一个${}_2$乙${}_2$双嵌段共聚物共混物与先前的实验和理论结果非常一致。该研究表明，二嵌段共聚物的二元共混物提供了一种有效的途径来调节复杂球形堆积相的出现和稳定性。