He Chaoliang, Sun Jingru, Zhao Ting, Hong Zhongkui, Zhuang Xiuli, Chen Xuesi, Jing Xiabin
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Graduate School of Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022, P. R. China.
Biomacromolecules. 2006 Jan;7(1):252-8. doi: 10.1021/bm050627f.
The crystallization behaviors of the poly(ethylene glycol)-poly(epsilon-caprolactone) diblock copolymer with the PEG weight fraction of 0.50 (PEG(50)-PCL(50)) was studied by DSC, WAXD, SAXS, and FTIR. A superposed melting point at 58.5 degrees C and a superposed crystallization temperature at 35.4 degrees C were obtained from the DSC profiles running at 10 degrees C/min, whereas the temperature-dependent FTIR measurements during cooling from the melt at 0.2 degrees C/min showed that the PCL crystals formed starting at 48 degrees C while the PEG crystals started at 45 degrees C. The PEG and PCL blocks of the copolymer crystallized separately and formed alternating lamella regions according to the WAXD and SAXS results. The crystal growth of the diblock copolymer was observed by polarized optical microscope (POM). An interesting morphology of the concentric spherulites developed through a unique crystallization behavior. The concentric spherulites were analyzed by in situ microbeam FTIR, and it was determined that the morphologies of the inner and outer portions were mainly determined by the PCL and PEG spherulites, respectively. However, the compositions of the inner and outer portions were equal in the analysis by microbeam FTIR.
通过差示扫描量热法（DSC）、广角X射线衍射（WAXD）、小角X射线散射（SAXS）和傅里叶变换红外光谱（FTIR）研究了聚乙二醇-聚己内酯二嵌段共聚物（PEG重量分数为0.50，即PEG(50)-PCL(50)）的结晶行为。在以10℃/min的速率运行的DSC曲线中，获得了58.5℃的叠加熔点和35.4℃的叠加结晶温度，而在以0.2℃/min的速率从熔体冷却过程中进行的温度相关FTIR测量表明，PCL晶体在48℃开始形成，而PEG晶体在45℃开始形成。根据WAXD和SAXS结果，共聚物的PEG和PCL嵌段分别结晶并形成交替的片层区域。通过偏光显微镜（POM）观察了二嵌段共聚物的晶体生长。通过独特的结晶行为形成了有趣的同心球晶形态。通过原位微束FTIR对同心球晶进行了分析，确定其内部和外部的形态分别主要由PCL球晶和PEG球晶决定。然而，在微束FTIR分析中，内部和外部的组成是相等的。
