Wanamaker Carolyn L, Tolman William B, Hillmyer Marc A
Institute of Technology Characterization Facility, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
Biomacromolecules. 2009 Feb 9;10(2):443-8. doi: 10.1021/bm801292v.
The hydrolytic degradation of polylactide-polymenthide-polylactide triblock copolymers (37 degrees C, pH 7.4) is compared to that of the component homopolymers. In addition to mass loss and water uptake measurements, size exclusion chromatography (SEC), 1H NMR spectroscopy, differential scanning calorimetry (DSC), and mechanical testing were used to monitor property changes during degradation. The rate of copolymer degradation was significantly influenced by the molecular weight of the polylactide end blocks. Mass loss of the polylactide homopolymer and the copolymer samples was observed once a decrease in the total molecular weight of the samples of 20% occurred. 1H NMR spectroscopy and DSC analysis of the copolymers during degradation revealed that the released oligomers contained mostly polylactide. After initial water uptake in which the mechanical properties were compromised to an extent, the Young's modulus and elongation at break of the biorenewable copolymers remained relatively unperturbed for up to 16 weeks, with significant retention of thermoplastic elastomeric properties for up to 21 weeks.
将聚丙交酯-聚乙交酯-聚丙交酯三嵌段共聚物在37摄氏度、pH 7.4条件下的水解降解情况与各组分均聚物的水解降解情况进行了比较。除了质量损失和吸水率测量外，还使用尺寸排阻色谱法（SEC）、1H核磁共振光谱法、差示扫描量热法（DSC）和力学测试来监测降解过程中的性能变化。共聚物的降解速率受到聚丙交酯端基链段分子量的显著影响。当样品的总分子量下降20%时，观察到聚丙交酯均聚物和共聚物样品的质量损失。对降解过程中的共聚物进行1H核磁共振光谱和DSC分析表明，释放出的低聚物主要含有聚丙交酯。在最初的吸水率阶段，力学性能在一定程度上受到损害，之后生物可再生共聚物的杨氏模量和断裂伸长率在长达16周的时间内保持相对稳定，在长达21周的时间内热塑性弹性体性能得到显著保留。
