中文摘要：

以无毒性的辛酸镁为催化剂催化L-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.首先用1H-NMR跟踪了共聚合单体转化率,显示L-LA聚合速率显著快于ε-CL.用13C-NMR分析共聚物微观结构和计算单体单元平均序列长度（LLLe和LCe）,表明聚合过程中酯交换反应导致单元序列结构重新分布.随着反应进行,LLLe急剧下降而LCe逐渐增加后稍有降低,游程数逐渐增大,共聚物无规度提高.反应初期主要是一级酯交换反应,二级酯交换反应导致的CLC序列结构在反应后期才观察到.由Fineman-Ross法计算出L-丙交酯和ε-己内酯的竞聚率分别为rLA=23和rCL=0.22,表明在聚合反应初期L-LA单体优先插入聚合物增长链端,形成LL单元长嵌段结构.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.二级酯交换系数（TII[CLC]）随ε-CL含量增加而增大.对于整个组成范围内,根据竞聚率计算的LLLr值始终要大于聚合产物的LLLe,而LCr计算值小于或接近LCe实验值.因此,共聚物单元序列分布随共聚物投料比和反应时间而改变,趋向于无规分布.以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.所有共聚物只有一个玻璃化转变温度Tg,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.

英文摘要：

Poly（L-lactide-co-ε-caprolactone） P（LLA-co-CL） copolymers with various L-lactide/ε-caprolactone（L- LA/ε-CL） mole ratios were prepared by the ring opening copolymerization of L-LA and ε-CL using nontoxic magnesium octoate as a catalyst in bulk. The time-conversion curves of L-LA and ε-CL copolymefization were recorded by 1H-NMR. The results showed significantly more rapid polymerization of L-LA relative to ε-CL. The carbonyl carbon signals in 13 C-NMR are most sensitive to the sequence distributions of the lactidyl and caproyl units and used for calculating their average block length （ LLL＊ and Lc^e ）. Two modes of transesterification occurred during the copolymerization process and played an important role in the redistribution of comonomer sequences. With polymerization progress, LEEe decreased sharply and Lce increased at first and then decreased gradually, as a result, the run number （R） increased gradually and the extent of randomness enhanced. The CLC sequence formed by the second mode of transesterification was observed at the end of reaction. Then, the reactivity ratios of L-LA and ε-CL were measured to be rLA = 23 and rcL = 0.22, respectively, using the Fineman-Ross method. The results（ tEA 〉 1 and rCL 〈 I ） imply that L-lactide monomer added preferentially into the copolymer chain end in the first step of the reaction, resulting in the formation of long blocks of lactidyl unit in the polymer chain. The copolymer composition has a profound influence on the values of LLLe and Lce. Both LLLe and Lce increased as the relative proportions of their respective monomers increased. The transesterification coefficient of the second mode of lactidyl units （ TI [CLC] ） increased as the feed mole fraction of ε-CL increased. In terms of the overall feed compositions, the LLLr values calculated from the reactivity ratio exceeded the LLLe values determined from the product; however, the Lce values were identical or shorter than the Lce values. Therefore, the repeat unit sequence