Studies on the synthesis and thermal properties of copoly(L-lactic acid/glycolic acid) by direct melt polycondensation
writer：Ping Lan, Yaopeng Zhang, Qinwei Gao, Huili Shao, Xuechao Hu
keywords：lactic acid/glycolic acid,melt polymerization,copolymerization, thermal properties,solubility
source：期刊
specific source：JOURNAL OF APPLIED POLYMER SCIENCE
Issue time：2004年
A two-step direct copolymerization process of L-lactic acid (L-LA)/glycolic acid (GA) was developed. The first step was to produce an oligomer of L-LA/GA and then the oligomer was polymerized with binary catalyst tin chloride dihydrate/rho-toluenesulfonic acid. In this way, the copoly(L-LA/GA) (PLGA), without any organic solvent, was synthesized directly. The thermal properties and solubility in chloroform of PLGA were studied by DSC and NMR. The results showed that the melting point of PLGA decreases with increasing mole fraction of GA units in copolymer. In addition, the melting point of polymer also decreased with increasing degree of racemization of polymer. The solubility of PLGA in chloroform decreased with the increase of the average lengths of the glycolic acid units. (C) 2004 Wiley Periodicals, Inc.