【作者】 刘慧；

【导师】 甘志华；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2016， 硕士

【摘要】 优良的生物相容性和生物降解性是结晶性脂肪族聚酯左旋聚乳酸(PLLA)和聚ε-己内酯(PCL)的突出性能,在组织工程领域,两者有很大的应用前景。但PLLA性脆而硬,而PCL韧性高但降解速率低,因此通过物理及化学方法将两者结合,通过二者的协同作用可以实现聚合物材料性能的改善以及表面结构、形貌及降解速率的调控,拓展其在生物医学领域中的应用。本论文的主要工作是以PLLA和PCL为结构单元构建不同化学结构的二元聚合物体系,系统研究化学结构及组成对其相容性、结晶行为和降解行为的影响,从而为材料表面结构与形貌及降解速率的调控提供理论依据。主要工作如下：首先以无毒的一元和二元醇为引发剂,通过调控单体与引发剂的摩尔比,合成一系列结构规整、组成可控的PLLA、PCL、左旋聚乳酸-b-聚￡-己内酯(PLLA-b-PCL)和聚(左旋丙交酯-CO-ε,-己内酯)(PLLA-co-PCL),从而构建一系列具有不同化学结构的二元聚合物体系：PLLA/PCL、 PLLA-b-PCL、PLLA-co-PCL。通过玻璃化温度的测定、一步及两步等温结晶以及非等温结晶和选择性降解,系统研究了化学结构及组成对二元聚合物的两相相容性、结晶行为以及降解行为的影响,研究结果表明PLLA与PCL的相容性可以通过化学结构调控,两者无规共聚时可以达到热力学程度上的相容。两相结晶性二元聚合物的结晶行为较为复杂,除受化学结构的影响外,还受两相组成以及热处理条件的影响。同时,研究表明,材料的降解速率以及表面形貌可以通过化学结构、组成以及凝聚态结构调控,为拓展其在组织工程领域中的应用提供了简单有效的方法。更多还原

【Abstract】 Both crystalline aliphatic poly (L-lactic acid) (PLLA) and poly (ε-caprolactone) (PCL) are promising as scaffolds in tissue engineering because of the excellent biocompatibility and biodegradability. However, PLLA is hard but brittle while PCL possesses high tenacity but low degradation rate. As a consequence, it is feasible to improve the performance of the polymers and adjust the surfaces structure, morphology and degradation rate by combining these two polymers with physical or chemical means, which can extend the application in biology and medical fields. In this work, a series of binary polymer systems were constructed with PLLA and PCL as structural unit, and the effects of chemical structure and composition on the compatibility, crystallization and degradation behavior of the polymer systems were systematically studied. The results will provide theoretic foundation for regulating the surface structure, morphology and degradation rate. The main work is as follows:Firstly, a series of PLLA, PCL, PLLA-b-PCL and PLLA-co-PCL with well-defined structure and tunable composition are synthesized with monohydric or dihydric alcohols as initiators. Consequently, the binary polymers with various chemical structures are obtained, namely PLLA/PCL blends, PLLA-b-PCL block copolymers and PLLA-co-PCL random copolymers.Then, the effect of chemical structure and composition on compatibility, crystallization and degradation behavior is studied by the measurement of glass transition temperature, one-step and two-steps isothermal crystallization, non-isothermal crystallization and selective degradation. It is indicated that the compatibility between PLLA and PCL phase can be modified by adjusting the chemical structure and it can achieve thermodynamic degree of compatibility for random copolymers. Crystalline/crystalline binary polymers show complicated crystallization behaviors which is influenced not only by chemical structure but also by binary composition and heat treatment condition. Meanwhile, the results indicate that the degradation rate and surface morphology can be modified by adjusting chemical structure, composition and condensed state structure, which supply a simple and effective method for extending the application in tissue engineering field.更多还原