Phase behavior and structure formation for diblock copolymers composed of side-chain liquid crystalline and glassy amorphous components
Phase behavior and structure formation for diblock copolymers composed of side-chain liquid crystalline and glassy amorphous components
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DOI：
10.1016/j.polymer.2008.11.003
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发表时间：
2009-01
期刊：
影响因子：
4.6
通讯作者：
Hiroki Takeshita;Shin-ichi Taniguchi;Mitsuo Arimoto;M. Miya;K. Takenaka;T. Shiomi
中科院分区：
文献类型：
--
作者：
Hiroki Takeshita;Shin-ichi Taniguchi;Mitsuo Arimoto;M. Miya;K. Takenaka;T. Shiomi
采用时间分辨小角X射线散射技术(SAXS)、差示扫描量热法和偏光光学显微镜研究了由聚[11-(4′-氰基苯基-4″-苯氧基)十一烷基丙烯酸酯](PA11OCB)和聚苯乙烯(PSt)组成的侧链液晶(LC)嵌段共聚物的液晶相行为和结构形成。 PA11OCB 均聚物形成近晶（Sm）液晶。嵌段共聚物的液晶行为取决于分子量和嵌段组成。当分子量相对较低时，观察到有序-无序转变（ODT）。在冷却此类嵌段共聚物时，液晶似乎正在等待 ODT 形成富含 LC 的微相。对于相对较高分子量的嵌段共聚物，液相结晶稍微增大了畴间距，但没有改变熔体中的微相分离结构。随着液晶微域维数的降低，液晶相的有序度也随之降低，即液晶块在基质或层状微相中形成近晶液晶，而圆柱微相中的液晶则不呈现近晶，而可能呈现向列液晶。此外，球形微区内的液晶块没有液晶化。从施加剪切流的 2-D SAXS 来看，Sm 层垂直于微相分离界面取向。液晶相层厚与分子量之间的关系表明主链正常延伸至微相分离界面。
Phase behavior and structure formation in liquid crystallization of a side-chain liquid crystalline (LC) block copolymers composed of poly[11-(4′-cyanophenyl-4″-phenoxy)undecyl acrylate] (PA11OCB) and polystyrene (PSt) were investigated by using a time-resolved small-angle X-ray scattering technique (SAXS), differential scanning calorimetry and polarizing optical microscopy. PA11OCB homopolymer formed smectic (Sm) liquid crystal. Liquid crystallization behavior of the block copolymers depended on the molecular weight and the block composition. When molecular weight was relatively low, order–disorder transition (ODT) was observed. In cooling of such block copolymers, liquid crystallization seemed to wait for the formation of LC-rich microphase by ODT. For the block copolymers with relatively high molecular weight, liquid crystallization slightly enlarged the domain spacing without changing the microphase separation structure in the melt. The order of the LC phase was lowered with decreasing dimensionality of the LC microdomains, that is, the LC blocks formed smectic liquid crystal in the matrix or lamellar microphase while liquid crystallization in the cylindrical microdomains did not show smectic but maybe nematic liquid crystal. Moreover, the LC blocks within the spherical microdomains did not liquid crystallize. From the 2-D SAXS with applying shear flow, the Sm layers were orientated perpendicularly to the interface of the microphase separation. The relation between the layer thickness of the LC phase and the molecular weight suggested that the main chain was extended normally to the interface of the microphase separation.