Trilayered Single Crystals with Epitaxial Growth in Poly(ethylene oxide)-block-poly(蔚-caprolactone)-block-poly(l-lactide) Thin Films

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• 作者：Yeo-Wan Chiang ; You-Yuan Hu ; Jhen-Ning Li ; Shih-Hung Huang ; Shiao-Wei Kuo
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：December 8, 2015
• 年：2015
• 卷：48
• 期：23
• 页码：8526-8533
• 全文大小：561K
• ISSN：1520-5835

文摘

Manipulation of crystalline textures of biocompatible block copolymers is critical for the applications in the medical field. Here, we present the control of multiple-crystalline morphologies with flat-on chain orientation in biocompatible poly(ethylene oxide)-block-poly(蔚-caprolactone)-block-poly(l-lactide) (PEO鈥揚CL鈥揚LLA) triblock copolymer thin films using melt and solvent-induced crystallizations. Only single-crystalline morphologies of the first-crystallized blocks can be obtained in the melt-crystallized thin films due to the confinement effect. With solvent annealing by PCL-selective toluene, single-crystalline PLLA to double-crystalline PLLA/PCL and to triple-crystalline PLLA/PCL/PEO layered crystals in sequence are observed for the first time. With the control of solvent selectivity, different sequential crystallization involving first-crystallized PCL transferring to double-crystalline PCL/PLLA is obtained using PEO-selective n-hexanol for annealing. Surprisingly, the crystalline growth of the trilayered single crystal exhibits specific layer-by-layer epitaxial relationship. As a result, the multiple-crystalline textures of the PEO鈥揚CL鈥揚LLA thin films can be carried out by controlling solvent and polymer interaction.