Liu Meijiao, Qiang Yicheng, Li Weihua, Qiu Feng, Shi An-Chang
State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, Fudan University, Shanghai 200433, China.
Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1.
ACS Macro Lett. 2016 Oct 18;5(10):1167-1171. doi: 10.1021/acsmacrolett.6b00685. Epub 2016 Oct 3.
The emergence of the complex Frank-Kasper phases from binary mixtures of diblock copolymers is studied using the self-consistent field theory. The relative stability of different ordered phases, including the Frank-Kasper σ and 15 phases containing nonspherical minority domains with different sizes, is examined by a comparison of their free energy. The resulting phase diagrams reveal that the σ phase occupies a large region in the phase space of the system. The formation mechanism of the σ phase is elucidated by the distribution of the two diblock copolymers with different lengths and compositions. In particular, the segregation of the two types of copolymers, occurring among different domains and within each domain, provides a mechanism to regulate the size and shape of the minority domains, thus enhancing the stability of the Frank-Kasper phases. These findings provide insight into understanding the formation of the Frank-Kasper phases in soft matter systems and a simple route to obtain complex ordered phases using block copolymer blends.
利用自洽场理论研究了二嵌段共聚物二元混合物中复杂的Frank-Kasper相的出现。通过比较不同有序相的自由能，研究了包括Frank-Kasper σ相和15个含有不同尺寸非球形少数域的相在内的不同有序相的相对稳定性。所得相图表明，σ相在系统的相空间中占据很大区域。通过两种不同长度和组成的二嵌段共聚物的分布阐明了σ相的形成机制。特别是，两种共聚物在不同域之间和每个域内发生的分离，提供了一种调节少数域尺寸和形状的机制，从而增强了Frank-Kasper相的稳定性。这些发现为理解软物质系统中Frank-Kasper相的形成提供了见解，并为使用嵌段共聚物共混物获得复杂有序相提供了一条简单途径。
