聚吡咯衍生物的合成及液晶性能

系统论述了新型导电功能性液晶聚合物3-和N-液晶基元取代聚吡咯的合成和液晶行为。指出通过化学氧化聚合、电化学氧化聚合和脱卤缩合聚合可以获得液晶性聚吡咯衍生物。它们均显示热致液晶行为,且多数呈现近晶液晶相,少数呈现向列液晶相,有些具有2种近晶相,有些具有单变液晶性。N-液晶基元取代聚吡咯比3-位取代聚吡咯具有较高的液晶稳定性。较长的亚甲基间隔和极性的介晶基团能够使N-取代聚吡咯具有较大的液晶微区和稳定的液晶相。N-取代液晶聚吡咯在摩擦力的作用下还可以诱发单轴取向。这种热致液晶性聚吡咯衍生物的研究成功有希望克服聚吡咯难以成型加工的巨大障碍。

Synthesis and Liquid Crystalline Properties of Polypyrrole Derivatives

The synthesis and liquid crystalline(LC)behavior of LC 3 and N substituted polypyrroles,a new type of conducting LC polymer, are summarized systematically.It is pointed out that LC polypyrrole derivatives can be obtained through chemically oxidative polymerization,electrochemically oxidative polymerization and dehalogen polycondensation.They all possess thermotropic LC behavior,most of them show smectic LC phase,and a few of them show nematic LC phase.Some of them show two types of smectic LC phases and some of them show monotropic LC phase.The polypyrroles having the LC mesogens on N substituted position exhibit more stable LC state than those having the LC mesogens on 3 substituted position. Long methylene spacers and polar LC side chain can form large LC domains and then give stable LC state. Uniaxial orientation of LC N substituted polypyrrole can be formed by a friction technique.It is hopeful that the big intractability of the processing and formation of the polypyrrole could be overcome because of the successful preparation of polypyrrole derivatives exhibiting thermotropic liquid crystallinity.