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Title:: Effect of the catalyst amount and reaction time on the microstructure of poly(lactic-co-glycolic acid)5050 copolymer

作者:: 董浩; 马丽霞; 吴倩倩; 王宪朋; 朱爱臣; 李文明; 王勤; 王传栋; 刘阳△; 山东省药学科学院山东省医用高分子材料重点实验室，济南 250101

Author(s):: DONG Hao; MA Lixia; WU Qianqian; WANG Xianpeng; ZHU Aichen; LI Wenming; WANG Qin; WANG Chuandong; LIU Yang; Shandong Academy of Pharmaceutical Sciences, Shandong Provincial Key Laboratory of Biomedical Polymers, Jinan 250101, China

Keywords:: Poly(lactic-co-glycolic acid); Microstructure; Sequence length; Transesterification; Microblock

摘要:: 以辛酸亚锡为催化剂，通过本体开环聚合制备了丙交酯与乙交酯摩尔比为1∶1的乙交酯-丙交酯（poly(lactic-co-glycolic acid)，PLGA）5050共聚物。1H和13C-NMR结果表明，共聚物组成与单体投料比基本一致，聚合过程中酯交换反应导致序列结构重新分布，随反应时间的延长和催化剂用量的增多，共聚物的二级酯交换系数(TⅡ\[LGL\]或TⅡ\[GLG\])逐渐增大。共聚物平均序列长度（LLL或LGG）随反应时间的延长和催化剂用量的增多而逐渐减小，催化剂用量较多时，减小更为显著，共聚物由微嵌段向无规结构的方向转变。当催化剂用量为0.05%时，反应速度更温和，反应时间调控范围更大，更容易得到LGG为3～5的微嵌段共聚物。

Abstract:: PLGA5050 copolymers of lactide and glycolide in a mole ratio of 1:1 were prepared by ring-opening polymerization in bulk using stannous octoate as a catalyst. The results of 1H and 13C-NMR indicated that the copolymer composition was in agreement with the respective monomer feed mole ratio. The mode of transesterification in the polymerization process caused redistribution of comonomer sequence. With the increase of the catalyst amount and reaction time, the coefficient of the second mode of transesterification of glycolidyl (TⅡ\[LGL\]) or lactidyl (TⅡ\[GLG\]) increased steadily, while the average sequence length of copolymers (LLL or LGG) gradually decreased that the reduction was more significant when the amount of catalyst was larger, and the copolymer changed from a microblock to a random structure. As the amount of catalyst is 0.05%, the reaction speed is milder and the range of reaction time is larger, which makes it easier to obtain LGG 3～5 microblock copolymers.