聚(DL-丙交酯-co-ε-己内酯)的合成、结构与性能研究

Synthesis,microstructure and properties of poly(DL-lactide-co-ε-caprolactone) obtained by magnesium octoate

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。

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. Microstrueture analyses of the resulting copolymers were performed by means of ^13 CNMR spectroscopy. Two modes of transesterifieation 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 eaproyl units （LLL^e and Lec）. Both LLL^e and Lc^e 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 erystallinity and the length of the copolymer sequences. All the eopolymers exhibited a single Tg. The experimental Tgs were in agreement with the calculated values from Fox equation. It can be concluded that the eopolymers are random, or comprise a mixture of compatible block copolymers.