聚乳酸嵌段共聚物的制备及扩链研究

Preparation and chain-extension of polylactic acid block copolymer

为了获得性能更优良的聚乳酸材料,以乳酸、ε-己内酯、丁二酸酐为原料,采用梯度升温法合成了聚乳酸嵌段共聚物,用IPDI对其扩链.采用乌氏黏度法、FT-IR、1H-NMR、TGA及XRD等手段对产物进行了表征.FT-IR和1H-NMR测试结果显示,预期的聚乳酸嵌段共聚物成功合成;几种聚合方法中,以先合成端羟基活性低聚物P(LA-CL),再加丁二酸酐与之共聚合成的产物P(LA-CL/SA)分子量最高,扩链后的产物分子量提高不多;P(LA-CL/SA)的热稳定性比PLA的低;XRD结果显示P(LA-CL/SA)为无定形峰,结晶度比PLA低.与PLA相比,改性后的聚乳酸嵌段共聚物分子量提高,更易降解,柔韧性增加.

To obtain better performance of polylactic acid,the polylactic acid block copolymer was synthesized via linear heating method with lactic acid,ε-caprolactone and succinic anhydride.The block copolymers were chain-extended with IPDI,and characterized by viscosity-average molecular weight,FT-IR,1H-NMR,TGA and XRD.The FT-IR and 1H-NMR results showed that the block copolymers were synthesized successfully.The hydroxyl-terminated copolymers P（LA-CL） were synthesized first,and then by adding succinic anhydride the block copolymer was synthesized which was the highest molecular weight.Molecular weight of polymer was increased less after chain extension.TGA results showed that the thermal stability of copolymer P（LA-CL/SA） was lower than that of the PLA,and the P（LA-CL/SA） was amorphous material and its crystallinity was lower than that of PLA.The block copolymers have higher molecular weight,readily biodegradable and better flexibility than PLA.