CRYSTAL ORIENTATION AND MELTING BEHAVIOR OF POLY(ε-CAPROLACTONE) UNDER ONE-DIMENSIONALLY “HARD” CONFINED MICROENVIRONMENT

作     者：Xuan-bo Liu Yong-feng Zhao Xing-he Fan 陈尔强 

作者机构：Beijing National Laboratory for Molecular Sciences Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education College of Chemistry and Molecular Engineering Peking University Research Institute of Material Science Beijing Research Institute of Chemical Industry SINOPEC 

出 版 物：《Chinese Journal of Polymer Science》 (高分子科学（英文版）)

年 卷 期：2013年第31卷第6期

页      面：946-958页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070305[理学-高分子化学与物理] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 

基　　金：supported by the National Nature Science Foundation of China (Nos. 20774006  20990232  and 21074003) 

主　　题：Crystallization Melting Confinement Diblock copolymer Rod-coil. 

摘      要：Crystal orientation and melting behavior of poly（e-caprolactone） in a diblock copolymer of poly（e-caprolactone）- block-poly（2,5-bis[4-methoxyphenyl]oxycarbonyl）styrene） （PCL-b-PMPCS） was investigated. The degrees of polymerization of the PCL and PMPCS block are 200 and 98, respectively. With the PMPCS in a columnar liquid crystalline phase, the diblock is rod-coil one, which exhibits a lamellar phase morphology with the PCL layer thickness of 15.2 nm. Since the glass transition temperature of PMPCS block is much higher than the melting temperature of PCL, the crystallization of PCL is in a one-dimensionally ＂hard＂ confinement environment. Mainly on the basis of two-dimensional wide-angle X-ray diffraction experiments, we identified the orientation of PCL isothermally crystallized at various crystallization temperatures （Tos）. At high Tcs （To 〉 10 ℃）, the c-axis of the PCL crystal is along the layer normal of the microphase-separated sturcture. Decreasing Tc can result in the tilting of PCL c-axis with respect to the layer normal. The lower the Tc is, the more the c-axis inclines. Meanwhile, the b-axis of PCL remains perpendicular to the layer normal. At a very low Tc of-78 ℃, the orientation of the PCL crystals is completely random. For the samples isothermally crystallized at Tc 〈 10 ℃, double melting behavior can be observed. While the low temperature endotherm reflects the melting of the crystals originally formed at the Tc applied, the high temperature one is associated with the crystals subjected to the process of recrystallization/reorganization upon heating due to the annealing effect.