ABA型聚L-丙氨酸-聚乙二醇嵌段共聚物的合成及其表征

利用L-α-丙氨酸和三聚光气反应制备了N-羧基-α-丙氨酸-环内酸酐(NCA).以聚乙二醇(PEG)为原料.制备了端氨基聚乙二醇(PEG-NH₂),并以此作为引发剂,引发NCA开环聚合.合成了不同组成和分子量的聚L-丙氨酸-聚乙二醇(PLAA-PEG-PLAA)嵌段共聚物.利用IR、¹H NMR、DSC、WAXD、CD等方法对共聚物结构进行了表征.结果表明,PEG-NH₂引发NCA开环聚合得到的是嵌段共聚物,通过¹H NMR谱得到共聚物组成及数均分子量;引入PEG的结果使聚L-丙氨酸的亲水性有所改善;CD测诚结果表明共聚物在水溶液中主链主要以α-螺旋构象存在.

Synthesis and Characterization of an ABA Triblock Copolymer Consisting of Poly(L-Alanine Acid)as A Component and Poly(Ethylene Glycol)as B Component

N-Carboxy-L-Aianine acid anhydride (NCA) was synthesized by L-α-alanine and triphosgen. PEG was used to prepare amine-terminated poly(ethylene glycol) (PEG-NH₂), which was used to initiate NCA open ring polymerization and produce PLAA-PEG-PLAA block copolymers of various contents and molecular weights. The structural characteristics of copolymers were shown by IR、¹H NMR、DSC、WAXD、CD etc. The results showed that products of NCA open ring polymerization initiated by PEG-NH₂ were block copolymers. Copolymer's contents and number-average molecular weights were obtained by ¹H NMR. The hydrophilicity of PLAA were improved by adding PEG. The results of CD showed the copolymers in aqueous solution existed as α-helical conformation.