Synthesis of Novel Block Copolymers Containing Liquid Crystalline Segments by Anionic Living Polymerization

用不同的引发剂在四氢呋喃中进行了6-（对甲氧基联苯氧基）甲基丙烯酸酯(1)和6-（对氰基联苯氧基）甲基丙烯酸酯(2)的阴离子聚合。在一定条件下，(1)和(2)均进行阴离子活性聚合，定量得到分子量调控良好、分子量分布极窄（Mw/Mn<1.1）的聚合物。通过使用这些活性聚合物，成功地制备了具有良好定义的(1)或(2)与苯乙烯或甲基丙烯酸甲酯的新型嵌段共聚物。它们的结构为AB、BA、ABA和BAB型嵌段共聚物。它们具有控制良好的分子量和组成以及较窄的分子量分布。为了系统地研究热致转变行为与聚合物结构的关系，制备了不同分子量（3 000 ~ 30 000）的均聚物和不同分子量（5 000 ~ 10 000）、不同成分（20 ~ 80mol%）的嵌段共聚物。在一系列聚(1)s中，观察到晶体、近晶a和各向同性相之间的热致转变行为，并用分子量的函数来检验。用聚(2)s观察到向列相液晶。显示液晶相的温度范围也受聚(2)分子量的影响。在聚苯乙烯和(1)嵌段共聚物中，通过电子显微镜和小角度x射线观察到液晶和非晶态聚苯乙烯嵌段导致的微相分离。在显示液晶相的温度范围内，首先发现微畴的周期随温度的升高而减小。为此提出了一个新的模型。另一方面，尽管这些嵌段共聚物是微相分离的，但在striene和(2)的嵌段共聚物中没有观察到这种现象。

Anionic polymerization of 6- (p-methoxybiphenoloxy) methacrylate (1) and 6- (p-cyanobiphenoloxy) methacrylate (2) were carried out in THF with various initiators. Under specified conditions, both (1) and (2) underwent anionic living polymerization to afford quantitatively the polymers of well-regulated molecular weights and of extremely narrow molecular weight distributions (Mw/Mn<1.1). By using these living polymers, novel well-defined block copolymers of (1) or (2) with stirene or methyl methacrylate were successfully prepared. Their structures are AB,BA,ABA and BAB types of block copolymers. They possessed well-controlled molecular weights and compositions and narrow molecular weight distributions. In order to investigate systematically the relationship between thermotropic transition behavior and polymer structure, homopolymers with different molecular weights (3 000-30 000) and block copolymers with different molecular weights (5 000-100 000) and compositions (20-80mol%) were prepared.In a series of poly (1) s, the thermotropic transition behavior between crystal, smectic A,and isotropic phases was observed to be examined with a function of molecular weight. With poly (2) s, nematic liquid crystalline phase was observed. The temperature range showing liquid crystalline phase was also influenced by the molecular weight of poly (2). In the block copolymers of stirene and (1), microphase separation due to liquid crstalline and amorphous polystirene blocks was observed by electron microscopy and small-angle X-ray methods. Decrease of period of microdomain with temperature was first found in the temperature range showing liquid crystalline phase. A new model was proposed for this. On the otherhand, this phenomenon was not observed in the block copolymers of stirene and (2), although these block copolymers were microphase-separated.