A Transition from Cylindrical to Spherical Morphology in Diblock Copolymer Thin Films
A Transition from Cylindrical to Spherical Morphology in Diblock Copolymer Thin Films
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DOI：
10.1021/ma801892p
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发表时间：
2008-12-09
期刊：
影响因子：
5.5
通讯作者：
Jinnai, Hiroshi
中科院分区：
文献类型：
--
作者：
Niihara, Ken-ichi;Sugimori, Hidekazu;Jinnai, Hiroshi
采用透射电子显微断层扫描（tem）研究了聚苯乙烯-嵌段异戊二烯嵌段共聚物（SI）薄膜的微相分离结构。硅嵌段共聚物在体态表现为圆柱形微畴。采用旋涂法制备了不同厚度的嵌段共聚物薄膜，并对其进行了广泛的退火处理。有趣的是，尽管在大多数情况下观察到平行于衬底的圆柱形形貌，但在一定的薄膜厚度下发现了球形微畴。基于自洽场理论，利用计算机模拟研究了厚度依赖关系，得到了基于最小自由能的形态相图。我们发现圆柱形微畴的六边形晶格的畸变导致了微畴向球形微畴的形态转变。
Microphase-separated structures in poly(styrene-block-isoprene) (SI) block copolymer thin films were investigated by transmission electron microtomography (TEMT). The SI block copolymer showed cylindrical microdomains in the bulk state. Several block copolymer thin films with different thicknesses were prepared by spin-coating and were extensively annealed before the TEMT experiments. Intriguingly, although the cylindrical morphology orienting parallel to the substrate was observed in most of the cases, spherical microdomains were found at certain film thicknesses. The thickness dependence was investigated using a computer simulation based on the self-consistent-field theory, producing a morphological phase diagram based on minimizing free energy. We find that the distortion of the hexagonal lattice of the cylindrical microdomains caused the morphological transition to the spherical microdomains.