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以聚乙二醇为原料,采用四步反应,合成了二碳酸二叔丁酯单保护的氨基聚乙二醇(BOC-PEG-NH2);并以BOC-PEG-NH2为引发剂,引发丙交酯开环聚合,得到了叔丁氧基酰胺基聚乙二醇-聚乳酸嵌段共聚物(BOC-PEG-PLA)。在三氟乙酸二氯甲烷溶液中,脱去保护基团,得到了端氨基聚乙二醇-聚乳酸嵌段共聚物(NH2-PEG-PLA)。采用核磁共振氢谱(1H-NMR)、紫外光度仪(UV)表征各聚合物的结构,由凝胶色谱仪(GPC)测定嵌段共聚物的分子量以及分子量分布。结果表明:合成的氨基引发剂在无催化剂条件下能够引发丙交酯开环聚合,制得分子量高、分子量分布窄的双亲性共聚物。通过三氟乙酸脱保护得到了端氨基聚乙二醇-聚乳酸(NH2-PEG-PLA),且对分子量没有影响。
Polyethylene glycol was used as the raw material to synthesize the di-tert-butyl dicarbonate mono-protected amino polyethylene glycol (BOC-PEG-NH2) in four steps. Boc-PEG-NH2 Lactide ring opening polymerization, t-butoxy amide-based polyethylene glycol - polylactic acid block copolymer (BOC-PEG-PLA). In the trifluoroacetic acid dichloromethane solution, the protective group was removed to obtain the terminal amino polyethylene glycol - polylactic acid block copolymer (NH2-PEG-PLA). The structure of each polymer was characterized by 1H nuclear magnetic resonance (1H-NMR) and ultraviolet (UV) spectroscopy. The molecular weight and molecular weight distribution of the block copolymers were determined by gel permeation chromatography (GPC). The results show that the synthesized amino initiator can initiate the lactide ring-opening polymerization in the absence of catalyst and produce amphiphilic copolymer with high molecular weight and narrow molecular weight distribution. The terminal amino polyethylene glycol-polylactic acid (NH2-PEG-PLA) was obtained by deprotection of trifluoroacetic acid and had no effect on the molecular weight.