Poly(epsilon-caprolactone) polyurethane and its shape-memory property.
Poly(epsilon-caprolactone) polyurethane and its shape-memory property.
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DOI：
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发表时间：
2005
影响因子：
6.2
通讯作者：
Peng Ping;Wenshou Wang;Xuesi Chen;X. Jing
中科院分区：
文献类型：
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作者：
Peng Ping;Wenshou Wang;Xuesi Chen;X. Jing
以聚己内酯（PCL）二醇、2，4-甲苯二异氰酸酯和乙二醇为原料，合成了一系列嵌段聚己内酯聚氨酯（PCLU）。PCL的分子量（M（n））为500- 10，000，并且软硬摩尔比为1：2至1：6。它们的形状记忆行为作为PCL分子量，PCLU组合物，和热/机械历史的函数进行了研究。当选择比T（m）低15-20 ℃的变形温度时，最低回复温度（LRT）为比T（m）低15-18 ℃，并且对于300%的拉伸变形和2.7倍的压缩，回复率为94-100%。讨论了这种变形-恢复过程的原因和T（m）以下形状恢复的机理。形状恢复与变形和固定过程中形成的晶体的预熔化有关，因此，它可以在固态下完成。其驱动力是变形和结晶过程中变形试样中储存的内应力。因此，对于形状记忆PCLU来说，LRT是比T（m）更实用的温度。它可以方便地通过热机械分析测量。通过调节PCL二醇的分子量和软硬比，可以将PCLU的LRT调节到37-42 ℃范围，并在形状恢复后保持合理的刚性，满足医用敷料的基本要求。
A series of segmented poly(epsilon-caprolactone) polyurethanes (PCLUs) were prepared from poly(epsilon-caprolactone) (PCL) diol, 2,4-toluene diisocyanate and ethylene glycol. The molecular weight (M(n)) of PCL was 500-10,000, and the soft-to-hard molar ratio was 1:2 to 1:6. Their shape-memory behaviors were investigated as a function of PCL molecular weight, PCLU composition, and thermal/mechanical history. When a deformation temperature 15-20 degrees C below T(m) was chosen, the lowest recovery temperature (LRT) was 15-18 degrees C below T(m), and the recovery ratio was 94-100% for tensile deformation of 300% and for compression of 2.7-fold. The reasons for this deformation-recovery procedure and the mechanism for this shape recovery below T(m) were discussed. The shape recovery was associated with the premelting of the crystals formed during the deformation and fixation, and, thus, it could be accomplished in the solid state. Its driving force was the inner stress stored in the deformed specimen during deformation and crystallization. Therefore, the LRT was a more practical temperature for shape-memory PCLU than T(m). It could be conveniently measured by means of thermal mechanical analysis. By adjusting the molecular weight of the PCL diol and the hard-to-soft ratio, the LRT of PCLU could be adjusted to the range of 37-42 degrees C, and reasonable rigidity could be retained after shape recovery, fulfilling the essential requirements of medical implantations.