Characteristic Shear-Flow Orientation in LC Block Copolymer Resulting from Compromise between Orientations of Microcylinder and LC Mesogen
Characteristic Shear-Flow Orientation in LC Block Copolymer Resulting from Compromise between Orientations of Microcylinder and LC Mesogen
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DOI：
10.1021/ma0711036
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发表时间：
2007-08
期刊：
影响因子：
5.5
通讯作者：
M. Tokita;Mitsunori Adachi;S. Masuyama;Fumi Takazawa;J. Watanabe
中科院分区：
文献类型：
--
作者：
M. Tokita;Mitsunori Adachi;S. Masuyama;Fumi Takazawa;J. Watanabe
用宽角和小角x射线衍射方法研究了聚苯乙烯（PS）和侧链液晶聚合物（LCP）组成的二嵌段共聚物的剪切流取向。通过原子转移自由基聚合制备的两种二嵌段共聚物，其PS段的质量分数分别为0.13和0.21，并且形成了明确的微偏析结构，PS柱在LCP基体中呈六边形排列，LCP基体按温度升高顺序依次形成近晶a相、向列相和各向同性相。根据LCP基体中相的类型，可以观察到两种类型的剪切流动方向。向列温度下的剪切流动在速度方向上很好地定向了PS微柱和LC介元。这种平行b取向可以从微柱和LC介质在剪切流中的一般取向中得到。当LCP矩阵变换为近晶LC时，介元平行于速度梯度方向排列。
The shear flow orientation in the diblock copolymers composed of polystyrene (PS) and side-chain liquid crystal polymer (LCP) was investigated by the wide and small-angle X-ray diffraction methods. Two diblock copolymers prepared by atom transfer radical polymerization have the weight fractions of the PS segment of 0.13 and 0.21, and form a well-defined microsegregation structure with PS cylinders hexagonally packed in a matrix of LCP which forms smectic A, nematic, and isotropic phases in order of increasing temperature. Two types of shear flow orientation have been observed, depending on the type of the phase in the LCP matrix. The shear flow at nematic temperatures orients well the PS microcylinders as well as the LC mesogens in the velocity direction. This parallel-b orientation is expectable from the general orientation of the microcylinders and the LC mesogens in shear flow. When the LCP matrix transforms to the smectic LC, the mesogens are aligned parallel to the velocity gradient direction entaili...