Development of Novel Biodegradable Polymers with High Melting Temperature

今年，我们研究了去年合成的聚合物的一些性质和生物降解性。我们合成了熔融温度高于100ﾟC的以下共聚物：(R)-β-丁内酯[(R)-β-丁内酯-己内酯(CL)共聚物((R)-β-BL/CL&GT；75/25)，_L-丙交酯(_LLA)/CL&GT；(_L-LA/CL&GT；_L-LA与_L-DMO(_L-3，_<dl>6-二甲基-2，5-吗啉二酮；环状多肽之一)的共聚物(_L-LA/_L-DMO&gt；85/15)，发现_L-LA/_L-DMO共聚物被蛋白质等酶降解最多。结果表明，该共聚物的热性能和拉伸性能与聚(_L-LA)基本相同，但不能改善聚(_L-LA)的脆性(缺乏柔韧性)，因此我们制备了_L-LA/_L-DMO/CL三元共聚物；CL单元的引入有望改善聚(_L-LA)的脆性；并对共聚物的一些性能和生物降解性进行了测试。结果表明，CL含量约为10mol%的共聚物，如_L-LA/_L-DMO/CL(=88/4/8)共聚物具有较高的伸长率，保持了较好的拉伸强度和生物降解性。今后，我们将利用各种脱脂肽和内酯制备这类三元聚合物，并开发具有良好性能和生物降解性的新型可生物降解聚合物。

In this year, we have examined some properties and biodegradation of the polymers synthesized last year. Then, we have fed back the obtained results to polymer synthesis, and developed the polymers with good properties and biodegradability.We have prepared the following copolymers with melting temperature higher than 100ﾟC ; (R)-beta-butyrolactone [(R)-beta-BLupsilonepsilon-caprolactone (CL) copolymers ((R)-beta-BL/CL>75/25 ), _L-lactide (_LLA)/CL copolymers(_L-LA/CL>85/15) , and the copolymers of _L-LA with _L-DMO (_L-3, _<DL>6-dimethyl-2,5-morpholinedione ; one of cyclic depsipeptides) (_L-LA/_L-DMO>85/15) etc. The _L-LA/_L-DMO copolymers were degraded most by enzymes such as proteases.Subsequently, we have measured the thermal and mechanical properties of the _L-LA/_L-DMO (=92/8) copolymer. As a result, the thermal and tensile properties of this copolymer were kept at much the same levels as those of poly(_L-LA), however, the brittleness (the lack of flexibility) of poly(_L-LA) could not be improved Thus, we have prepared the _L-LA/_L-DMO/CL terpolymers ; the introduction of CL unit can be expected for improving the brittleness of poly(_L-LA) ; and examined some properties and biodegradability of the terpolymers. It has become apparent that the terpolymers containing ca 10mol% of CL unit, e.g., _L-LA/_L-DMO/CL (=88/4/8) copolymer shows a relatively high elongation, keeping good tensile strength and biodegradation. Henceforth, we will prepare these types of terpolymers, using various depsipeptides and lactones, and develop novel biodegradable polymers having both good properties and biodegradability.