Crystallization, melting, and enzymatic degradation of biodegradable poly(butylene succinate-co-14 mol % ethylene succinate) copolyester.
Crystallization, melting, and enzymatic degradation of biodegradable poly(butylene succinate-co-14 mol % ethylene succinate) copolyester.
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DOI：
10.1021/bm0056557
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发表时间：
2001-02
影响因子：
6.2
通讯作者：
Z. Gan;H. Abe;Y. Doi
中科院分区：
文献类型：
--
作者：
Z. Gan;H. Abe;Y. Doi
在30 ~ 90 ℃的较宽结晶温度范围内，研究了熔融结晶的聚丁二酸丁二醇酯-co-14mol%丁二酸乙二酯共聚物[P（BS-co-14mol%ES）]的晶体结构和生长动力学。通过广角X射线衍射（WAXD），确定了由BS和ES单元组成的嵌段共聚物与聚丁二酸丁二醇酯（PBS）均聚物具有相同的晶体结构，表明只有PBS序列结晶，而ES单元为无定形形式。根据二次成核理论，观察到了II和III两个区域，它们的转变温度约为80 ℃。随着结晶温度的升高，P（BS-co-14mol%ES）三元共聚物的球晶形貌由带状球晶向无带状消光的正常球晶转变。用差示扫描量热法（DSC）研究了不同条件下P（BS-co-14mol%ES）嵌段共聚物的熔融行为。在加热过程中，在熔融曲线上观察到四个熔融峰和一个膨胀峰，并对其成因进行了讨论。利用来自施氏假单胞菌（Pseudomonasstutzeri）的胞外聚羟基丁酸酯（PHB）解聚酶对熔融结晶的P（BS-co-14mol%ES）薄膜进行了酶促降解，并用原子力显微镜（AFM）对降解前后的层状晶体形貌进行了观察。结果表明，酶可降解的ES单元存在于层状晶体的表面上，并被酶水解，而由PBS链组成的结晶核心不被降解。
The crystal structure and growth kinetics of melt-crystallized poly(butylene succinate-co-14 mol % ethylene succinate) [P(BS-co-14 mol % ES)] copolyester have been investigated at a wide crystallization temperature range of 30 to 90 degrees C. By means of wide-angle X-ray diffraction (WAXD), the copolyester composed of BS and ES units has been identified to have the same crystal structure with that of poly(butylene succinate) (PBS) homopolymer, suggesting that only PBS sequences crystallize while that the ES units are in an amorphous form. On the basis of secondary nucleation theory, two regimes of II and III have been observed and their transition temperature is around 80 degrees C. The spherulitic morphologies of P(BS-co-14 mol % ES) copolyester developed from banded spherulites to the normal ones without banding extinction patterns as the crystallization temperature increased. The melting behavior of P(BS-co-14 mol % ES) copolyester under different conditions has been studied by differential scanning calorimetry (DSC). Four melting peaks and one exothermal peak on the melting curves were observed during heating process, and their origination is discussed. The enzymatic degradation was carried out on the melt-crystallized P(BS-co-14 mol % ES) thin film by an extracellar PHB depolymerase from Pseudomonas stutzeri and the morphologies of lamellar crystals before and after degradation have been examined by atomic force microscopy (AFM). The results have indicated that enzymatically degradable ES units exist on the surface of lamellar crystals and are hydrolyzed by the enzyme, while that the crystalline cores composed of PBS chains are not degraded.