不同氨基酸直接改性聚乳酸的性能研究

Studies on the properties of polylactic acid directly modified by different amino acids

分别以甘氨酸(Gly)和L-天冬氨酸(Asp)与L-乳酸(L-LA)直接熔融共聚制备改性聚乳酸(PLA),所得两种共聚物聚(乳酸-甘氨酸)[P(LA-co-Gly)]和聚(乳酸-天冬氨酸)[P(LA-co-Asp)]进行了表征。对P(LA-co-Gly),不同投料比时共聚物重均分子量(Mw)和分散度(Mw/Mn)随Gly投料量的增加而变小。与双官能团Gly直接改性的PLA相比,多官能团Asp直接改性的PLA具有一定的支链结构,分散度(Mw/Mn)二者接近或P(LA-co-Asp)的更高,但两种共聚物的Tg均比PLA的要大,亲水性有所提高。同时,所得共聚物均呈无定形态,且Mw都在2400到5600之间,能满足药物缓释对聚乳酸类高分子材料分子量的要求。

Polylactic acid（PLA） was modified by glycine（Gly） and aspartic acid（Asp） respectively.And two copolymers,poly（lactic acid-co-glycine） [P（LA-co-Gly）]and poly（lactic acid-co-aspartic acid） [P（LA-co-Asp）],were synthesized via direct melt copolycondensation starting from L-lactic acid（L-LA） and amino acids with different functional groups.The copolymers were systematically characterized with intrinsic viscosity [η],FTIR,1H NMR,GPC,DSC,XRD and contact angle testing.For P（LA-co-Gly）,with the increase of the molar feed ratio of Gly,Mw and Mw/Mn of P（LA-co-Gly） decreased gradually.Compared with PLA modified by Gly with two functional groups,PLA modified by Asp with multiple functional groups had branched chain structure.Mw/Mn of both copolymers are approximate or that of P（LA-co-Asp） was bigger,and both copolymers had bigger Tg and better hydrophilicity than unmodified PLA.At the same time,the copolymers with Mw from 2400 to 5600 were obtained and both were amorphous,which could meet the demand of drug delivery carrier material.