College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China.
Nanoscale. 2018 Dec 20;11(1):285-293. doi: 10.1039/c8nr07685e.
The self-assembly of a high-χ silicon-containing side-chain liquid crystalline block copolymer (LC BCP) in bulk and in thin films is reported, and the structural transition process from the hexagonally packed cylinder (HEX) to the body-centered cubic structure (BCC) in thin films was examined by both reciprocal and real space experimental methods. The block copolymer, poly(dimethylsiloxane-b-11-(4'-cyanobiphenyl-4-yloxy)undecylmethacrylate) (PDMS-b-P(4CNB11C)MA) with a molecular weight of 19.5 kg mol-1 and a volume fraction of PDMS 27% self-assembled in bulk into a hierarchical nanostructure of sub-20 nm HEX cylinders of PDMS with the P(4CNB11C)MA block exhibiting a smectic LC phase with a 1.61 nm period. The structure remained HEX as the P(4CNB11C)MA block transformed to an isotropic phase at ∼120 °C. In the thin films, the PDMS cylindrical microdomains were oriented in layers parallel to the substrate surface. The LC block formed a smectic LC phase which transformed to an isotropic phase at ∼120 °C, and the microphase-separated nanostructure transformed from HEX to BCC spheres at ∼160 °C. The hierarchical structure as well as the dynamic structural transition of the thin films were characterized using in situ grazing-incidence small-angle X-ray scattering and grazing-incidence wide-angle X-ray scattering. The transient morphologies from the HEX to BCC structure in thin films were captured by scanning electron microscopy and atomic force microscopy, and the transition pathway was described.
报道了一种高 χ 值含硅侧链液晶嵌段共聚物（LC BCP）在本体和薄膜中的自组装，并通过倒空间和实空间实验方法研究了薄膜中从六方堆积圆柱（HEX）到体心立方结构（BCC）的结构转变过程。嵌段共聚物聚二甲基硅氧烷-b-11-（4'-氰基联苯-4-基氧基）十一烷基甲基丙烯酸酯（PDMS-b-P（4CNB11C）MA），分子量为 19.5kg/mol，PDMS 的体积分数为 27%，在本体中自组装成亚 20nm 的 HEX 圆柱的分级纳米结构，其中 PDMS 具有向列液晶相，周期为 1.61nm。当 P（4CNB11C）MA 嵌段转变为各向同性相时，结构仍保持 HEX，温度约为 120°C。在薄膜中，PDMS 圆柱微区沿平行于基底表面的层取向。LC 嵌段形成向列液晶相，温度约为 120°C 时转变为各向同性相，微相分离的纳米结构在约 160°C 时从 HEX 转变为 BCC 球体。通过原位掠入射小角 X 射线散射和掠入射广角 X 射线散射对薄膜的分级结构和动态结构转变进行了表征。用扫描电子显微镜和原子力显微镜捕获了薄膜中从 HEX 到 BCC 结构的瞬态形态，并描述了转变途径。
