以外消旋乳酸(D,L—LA)为单体,与L-谷氨酸(L-Glu)直接熔融聚合,合成了生物降解材料聚(乳酸-谷氨酸)共聚物。用特性粘数[η]、FTIR、1H NMR、GPC、DSC、XRD等手段进行系统表征,探讨了催化刺种类和用量、熔融聚合反应时间、反应温度以及不同投料比对聚合物合成的影响。在单体乳酸和谷氨酸投料物质的量比为98:2、150℃、70Pa、催化剂snCl2的用量0.7%(质量分数)的条件下熔融聚合8h,聚合物重均相对分子质量(Mw)可达6400。随着谷氨酸投料量的增加,共聚物重均相对分子质量逐渐减小,L均低于直接熔融合成的聚外消旋乳酸,且共聚物均为无定形态。
Using D,L-lactic acid(D,L-LA) and L-glutamic acid(L-Glu) as monomers, biodegradable material poly(lactic acid-eo-glutamic acid) [P(LA-co-Glu)] is synthesized by direct melt copolycondensation. The copolymer is systematically characterized with intrinsic viscosity [η], FTIR, 1H NMR, GPC, DSC and XRD. The influences of different synthetic conditions, including kinds and quantity of catalyst, time, temperature of melt copolycondensation and different molar.feed ratio on the polymer are discussed in detail. Under the conditions of molar feed ratio of LA/ Glu 98/2, amount of catalyst SnCl2 0. 7%, copolymerization temperature 150℃ and time 8h, pressure 70Pa, the co- polymerization give the polymer with maximum Mw 6400. With the increase of the molar feed ratio of Glu, the Mw of the copolymer decreases gradually, all data of Tg are lower than that of homopolymer poly(D,L-lactic acid) synthesized by direct melt polycondensation and all eopolymers are amorphous.