Hierarchical supramolecular ordering with biaxial orientation of a combined main-chain/side-chain liquid-crystalline polymer obtained from radical polymerization of 2-vinylterephthalate.
Hierarchical supramolecular ordering with biaxial orientation of a combined main-chain/side-chain liquid-crystalline polymer obtained from radical polymerization of 2-vinylterephthalate.
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DOI：
10.1021/ja101184u
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发表时间：
2010-05
影响因子：
15
通讯作者：
He-Lou Xie;Chang-Kai Jie;Zhenqiang Yu;Xuanbo Liu;Hailiang Zhang;Zhihao Shen;E. Chen;Qifeng Zhou
中科院分区：
文献类型：
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作者：
He-Lou Xie;Chang-Kai Jie;Zhenqiang Yu;Xuanbo Liu;Hailiang Zhang;Zhihao Shen;E. Chen;Qifeng Zhou
用差示扫描量热法、一维和二维广角X射线衍射仪(一维和二维广角X射线衍射仪)和偏光显微镜研究了聚(2，5-双[[6-(4-丁氧基-4‘-氧基联苯基)己基]氧羰基}苯乙烯)自由基聚对苯二甲酸乙二酯的主链/侧链组合液晶聚合物(MCSCLCP)的液晶相结构和相变。我们发现，分子量足够大的1在低温下可以在纳米和亚纳米尺度上自组装成具有双排序的分级结构。1的主链是棒状的，这是由于侧链的中央刚性部分横向连接到沿着聚乙烯主干的每两个碳原子而产生的“夹套”效应的结果，形成了2D中心的矩形支架。含联苯的侧链填充主链之间的空间，形成近晶E(SME)状结构，侧链轴线垂直于主链轴线。通过三个正交方向的二维WAXD实验证实了1的这种双轴取向。当SME类填料在高温下熔化时，主链支架仍然存在。进一步加热可以得到正常的近晶A(SMA)结构，然后是各向同性状态。我们发现，当外加电场时，主链支架对联苯的运动有很大的抑制作用。当主链在SMA相中获得足够高的迁移率时，在相当弱的电场下可以获得宏观取向1，这意味着主链和侧链可以沿垂直方向协同运动。我们的工作表明，当两个独立的组分同时引入侧链时，得到的聚合物可以描述为具有迷人的层次化有序结构的MCSCLCP。
The liquid-crystalline (LC) phase structures and transitions of a combined main-chain/side-chain LC polymer (MCSCLCP) 1 obtained from radical polymerization of a 2-vinylterephthalate, poly(2,5-bis{[6-(4-butoxy-4'-oxybiphenyl) hexyl]oxycarbonyl}styrene), were studied using differential scanning calorimetry, one- and two-dimensional wide-angle X-ray diffraction (1D and 2D WAXD), and polarized light microscopy. We have found that 1 with sufficiently high molecular weight can self-assemble into a hierarchical structure with double orderings on the nanometer and subnanometer scales at low temperatures. The main chains of 1, which are rodlike as a result of the "jacketing" effect generated by the central rigid portion of the side chains laterally attached to every second carbon atom along the polyethylene backbone, form a 2D centered rectangular scaffold. The biphenyl-containing side chains fill the space between the main chains, forming a smectic E (SmE)-like structure with the side-chain axis perpendicular to that of the main chain. This biaxial orientation of 1 was confirmed by our 2D WAXD experiments through three orthogonal directions. The main-chain scaffold remains when the SmE-like packing is melted at elevated temperatures. Further heating leads to a normal smectic A (SmA) structure followed by the isotropic state. We found that when an external electric field was applied, the main-chain scaffold greatly inhibited the motion of the biphenyls. While the main chains gain a sufficiently high mobility in the SmA phase, macroscopic orientation of 1 can be achieved using a rather weak electric field, implying that the main and side chains with orthogonal directions can move cooperatively. Our work demonstrates that when two separate components, one offering the "jacketing" effect to the normally flexible backbone and the other with mesogens that form surrounding LC phases, are introduced simultaneously into the side chains, the polymer obtained can be described as an MCSCLCP with a fascinating hierarchically ordered structure.