Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore.
Biomaterials. 2010 Nov;31(32):8132-40. doi: 10.1016/j.biomaterials.2010.07.043. Epub 2010 Aug 17.
Block co-polymers PCTBVs (M(n) of 36,300-65,300 g/mol, T(m) of 39-40 and 142 degrees C) containing hyperbranched three-arm poly(epsilon-caprolactone) (PCL) as switching segment and microbial polyester PHBV as crystallizable hard segment were designed as biodegradable shape-memory polymer (SMP) for fast self-expandable stent and synthesized in 96% yield by the reaction of three-arm PCL-triol (M(n) of 4200 g/mol, T(m) of 47 degrees C) with methylene diphenyl 4,4'-diisocyanate isocynate (MDI) to form the hyperbrached MDI-linked PCL (PTCM; M(n) of 25,400 g/mol and a T(m) of 38 degrees C), followed by further polymerization with PHBV-diol (M(n) of 2200 g/mol, T(m) of 137 and 148 degrees C). The polymers were characterized by (1)H NMR, GPC, DSC, tensile test, and cyclic thermomechanical tensile test. PCTBVs showed desired thermal properties, mechanical properties, and ductile nature. PCTBV containing 25 wt% PHBV (PCTBV-25) demonstrated excellent shape-memory property at 40 degrees C, with R(f) of 94%, R(r) of 98%, and shape recovery within 25s. PCTBV-25 was also shown as a safe material with good biocompatibility by cytotoxicity tests and cell growth experiments. The stent made from PCTBV-25 film showed nearly complete self-expansion at 37 degrees C within only 25 s, which is much better and faster than the best known self-expandable stents.
嵌段共聚物 PCTBVs（数均分子量 36300-65300g/mol，熔点 39-40 和 142°C），含有超支化三臂聚（ε-己内酯）（PCL）作为开关段和微生物聚酯 PHBV 作为可结晶硬段，被设计为可生物降解的形状记忆聚合物（SMP），用于快速自扩张支架，并通过三臂 PCL-三醇（数均分子量 4200g/mol，熔点 47°C）与亚甲基二苯基 4,4'-二异氰酸酯（MDI）反应以 96%的产率合成，形成超支化的 MDI 连接的 PCL（PTCM；数均分子量 25400g/mol，熔点 38°C），然后与 PHBV-二醇（数均分子量 2200g/mol，熔点 137 和 148°C）进一步聚合。聚合物通过（1）H NMR、GPC、DSC、拉伸试验和循环热机械拉伸试验进行了表征。PCTBV 表现出理想的热性能、机械性能和韧性。含 25wt%PHBV 的 PCTBV（PCTBV-25）在 40°C 下表现出优异的形状记忆性能，回复率（R(f)）为 94%，回复率（R(r)）为 98%，且在 25s 内完成形状恢复。通过细胞毒性试验和细胞生长实验，PCTBV-25 还表现出良好的生物相容性，是一种安全的材料。由 PCTBV-25 薄膜制成的支架在 37°C 下仅需 25s 即可实现近乎完全的自扩张，这比最知名的自扩张支架要好得多，速度也快得多。
