【摘要】 以辛酸镁为催化剂催化DL-丙交酯和ε-己内酯本体开环共聚合,制备了一系列不同单体配比的共聚物1。3CNMR分析了共聚物微观结构,计算各单元平均序列长度,表明两类酯交换反应存在使得单元序列结构重新分布,并趋向于无规化分布;共聚物组成显著影响单元序列长度,各序列长度随相应单体加入量增加而增长。DSC和XRD分析了共聚物热性能和结晶性,表明共聚物结晶性与单元序列长度密切相关。共聚物只观察到一个玻璃化转变温度,符合无规共聚物的Fox方程,说明所得共聚物为无规共聚物,或者说包含有相容性嵌段成分的共聚物。更多还原

【Abstract】 Poly(DL-lactide-co-ε-caprolactone) copolymers were prepared by copolymerization of DL-LA and ε-CL using nontoxic magnesium octoate as catalyst in bulk.Microstructure analyses of the resulting copolymers were performed by means of 13CNMR spectroscopy.Two modes of transesterification occurred during the copolymerization process and played an important role in the redistribution of comonomer sequences toward randomness.The copolymer composition has a profound influence on the average block length of lactidyl and caproyl units(LeLL and LeC).Both LeLL and LeC increased as the relative proportions of their respective monomers increased.The thermal properties and crystallization of the copolymers were investigated by DSC and XRD.The results showed that a close relationship between copolymer crystallinity and the length of the copolymer sequences.All the copolymers exhibited a single Tg.The experimental Tgs were in agreement with the calculated values from Fox equation.It can be concluded that the copolymers are random,or comprise a mixture of compatible block copolymers.更多还原