两亲型聚L-亮氨酸-聚乙二醇单甲醚嵌段共聚物的合成与表征

开环聚合;生物降解共聚物;两亲型聚L-亮氨酸-聚乙二醇单甲醚嵌段共聚物的合成与表征

Synthesis and Characterization of Amphiphilic Diblock Copolymers of Poly(L-Leucine) with Poly(Ethylene Glycol) Monomethyl Ether

A series of amphiphilic diblock copolymers poly (L-leucine acid )-b-poly (ethylene glycol) monomethyl ether of lifterent molecular weights were synthesized by the ring-opening polymerization of L-leucine N-carboxy anhydride (NCA) onto amine-terminated poly(ethylene glycol) monomethyl ether (MPEG-NH_2 ) as a macroinitiator. Their structures and properties were characterized by IR, ~1H NMR, DSC, GPC and wateruptake measurements. The results showed that the copolymer samples from the ring opening polymerization of NCA had the expected block structures. The block contents and number-average molecular weights of the copolymers, calculated based on the data of ~1H NMR spectra, could be adjusted by changing the feeding ratio of NCA to the macroinitiator. Owing to incorporation of the hydrophilic MPEG block, the hydrophilicity of these diblock copolymers was much improved than that of the homopolymer poly(L-leucine).