Herein, this work aims to demonstrate the topological effect on the mechanicalx characteristics of self-assembled block copolymers (BCPs). The lamellae-forming polystyrene--polydimethylsiloxane (PS--PDMS) can be self-assembled into various nanostructured monoliths with the use of PS-selective solvent for solvent annealing, giving diamond, gyroid, and cylinder structures with increasing the swelling degree of PS domain (the effective volume fraction of the PS segment after solvent annealing followed by evaporation). The stiffness of the self-assembled monoliths is scrutinized by nanoindentation test. For intrinsic PS--PDMS monolith with lamellar structure, the reduced elastic modulus as calculated from the measured stiffness is 0.91 GPa. By contrast, the PS--PDMS monolith with cylinder structure gives a significant reduction in reduced elastic modulus with the value of 0.52 GPa due to the introduced microporosity to the PS domain from solvent annealing using PS-selective solvent, resulting in the lower confrontation for continuous layer-by-layer deformation of hard PS and soft PDMS domains. In the case of gyroid-structured PS--PDMS monolith, it is unexpected to exhibit a significant increase in the reduced elastic modulus with a value of 1.6 GPa: note that the effect of microporosity is still significant. Accordingly, the enhancement of the reduced elastic modulus is attributed to the effect of deliberate structuring with network topology ( three-dimensional co-continuous hard PS and soft PDMS domains) that is able to hold the occurrence of large-scale deformation. In contrast to the gyroid with a three-strut texture, the diamond-structured PS--PDMS monolith with a four-strut texture is superior to the gyroid with a reduced elastic modulus of 2.2 GPa, further confirming the suggested topology effect.

中文翻译：

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拓扑对自组装嵌段共聚物力学性能的影响

在此，这项工作旨在证明拓扑对自组装嵌段共聚物（BCP）机械特性的影响。利用PS选择性溶剂进行溶剂退火，形成片层的聚苯乙烯-聚二甲基硅氧烷（PS--PDMS）可以自组装成各种纳米结构整体，随着PS的溶胀度增加，得到金刚石、螺旋体和圆柱体结构域（溶剂退火后蒸发后 PS 段的有效体积分数）。通过纳米压痕测试来检查自组装整体的刚度。对于具有层状结构的内在 PS--PDMS 整体材料，根据测量的刚度计算得出的折合弹性模量为 0.91 GPa。相比之下，由于使用 PS 选择性溶剂进行溶剂退火，在 PS 域中引入了微孔，因此具有圆柱结构的 PS--PDMS 整体材料的降低弹性模量显着降低，值为 0.52 GPa，从而导致较低的对抗性。硬PS和软PDMS域的连续逐层变形。对于螺旋结构的 PS-PDMS 整体材料，出乎意料的是，折合弹性模量显着增加，值为 1.6 GPa：请注意，微孔率的影响仍然很显着。因此，降低弹性模量的增强归因于网络拓扑（三维共连续硬PS和软PDMS域）的故意结构的效果，能够抑制大规模变形的发生。与具有三支柱纹理的陀螺仪相比，具有四支柱纹理的金刚石结构PS-PDMS整体材料优于具有降低的弹性模量2.2 GPa的陀螺仪，进一步证实了所提出的拓扑效应。