摘要
以联苯二酚、取代对苯二酚及含氟酮单体为原料 ,通过亲核取代反应 ,合成了系列具有液晶性的新型聚芳醚酮 .研究了聚合物分子结构与性能之间的关系 .由于结晶相是从有序的液晶相转化形成的 ,故侧基含量的增加对液晶聚合物的融熔转变温度无显著影响 .聚合物的液晶稳定性受侧基影响较大 ,含极性侧基的氯取代聚合物的液晶温区比含大空阻侧基的聚合物的液晶温区小得多 ,说明空间几何因素比极性因素对液晶稳定性的影响大 .不同分子量聚合物有不同的液晶有序结构 ,低分子量聚合物具有高有序液晶结构 ,而高分子量聚合物只有低有序的向列相结构 .
Series of thermotropic liquid crystalline poly(aryl ether ketone)s were synthesized by mucleophilic substitution reactions of \{4,4′-biphenol\} and substituted hydroquinone with different difluoromonomers. The relationship between structure and properties of the novel copolymers was investigated. For the copolymers with liquid crystalline properties, their melting transition temperatures show no great change with increase the content of the crystal-disrupting unit. The reason is that the crystal phase is directly transformed from the ordered liquid crystal phase. Side-groups have important effect on mesophase stability. The temperature range of mesophase stability for the chloro-polymers is smaller than those of other series of copolymers(p-phenyl,t-butyl, methoxy, 3-trifluoromethylbenzene). This behavior indicates that the effect of geometric repulsive factor on the thermodynamic stability of the mesophase is much larger than that of the polarizability attractive factor. Different ordered liquid crystal phases are observed in the polymers with different molecular weights. At low molecular weight, highly ordered smectic liquid crystal phases form. With increasing the molecular weight, the ordered degree of the liquid crystals decreases, and only the nematic liquid crystal phase is observed in the polymer with higher molecular weight.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2001年第2期334-337,共4页
Chemical Journal of Chinese Universities
基金
国家自然科学基金! (批准号 :2 99740 32 )
国家科技部基础性研究重大项目! (批准号 :G 12 )资助
关键词
聚芳醚酮
液晶聚合物
结构
性能
Poly(aryl ether ketone)s
Liquid crystalline polymers
Structure and properties
