固体变温高分辨核磁共振碳谱研究聚氨酯型热致液晶高聚物

Solid-state High-resolution Variable-temperature￣(13)C NMR Shudy on HDI Based Main-chain Liquid Crystalline Elastomer

对由聚四氟呋喃预聚体、六次亚甲基二异氰酸酯及４，４＇－二羟乙氧基联苯按１：３：２的比例用两步法聚合得到的主链型聚氨酯热致液晶聚合物，采用变温固体高分辨核磁共振碳谱方法，在室温到１００℃范围内对该样品的聚集态结构、氢键相互作用、分子运动等变化进行了研究。在变温谱中，观察到硬段羰基形成的氢键随温度升高而逐渐解离以及ＨＢ２的部分结晶发生次级转变等一些有意义的现象。

The solid-state high-resolution variable-temperature￣(13)C NMR experiments(including￣(13)C CP/MAS,￣(13)C PST/MAS,￣(13)C DD/MAS and contact time measurements)were carried out on a main-chain liquid-crystalline polyurethane elastomer based on poly(tetramethylene oxide)(PTMO),hexamethylene diisocyanate(HDI)and 4,4'-bishydroxyethyloxybiphenyl(HB2)from room-temperature to 96℃.The HDI and HB2 segments which play the role of hard segmehts of the elastomer were found to be crystalline.The inter-molecular or inter-segmental hydrogen-bonds formed between the carbonyl group and the NH group were found to gradually decompose with the increasing of temperature,A secondary transition of the HB2 crystal was observed at temperatures well below the meltingpoint of the sample.