直接熔融聚合法合成生物降解材料PLEG研究 V反应机理

Studies on the Direct Synthesis of Biodegradable Material PLEG via Melt Copolymerization V: Copolycondensation Mechanism of LA and PEG

直接以乳酸(LA)单体和聚乙二醇(PEG)为原料,通过直接熔融共聚法,合成了生物降解材料聚乳酸-聚乙二醇(PLEG),用特性粘数[η]、GPC、FTIR1、H NMR、DSC和X-射线衍射等手段对其进行了系统的表征,发现许多因素对PLEG存在一定的影响,如不同的预聚方式时PLEG的组成不同、左旋乳酸(L-LA)获得的共聚物相对分子质量不如外消旋乳酸(D,L-LA)等。在此基础上,初步探讨了LA与PEG直接熔融共聚的反应机理。

Starting from lactic acid （LA） and polyethylene glycol （PEG）, the biodegradable material poly（lactic acid）-polyethylene glycol （PLEG） was directly synthesized via melt polycondensation, and characterized with intrinsic viscosity, GPC, FTIR,^ 1H NMR, DSC and X-ray diffraction. It was found that many synthetic factors had influences on the PLEG, especially the composition of PLEG was different when using different prepolymerization methods, and the copolymer＇s weight average relative molecular weight （Mw） when starting from L-lactic acid （L-LA） was lower than using D, L-lactic acid （ D, L-LA） as material. Based on the above facts, the copolycondensation mechanism of LA and PEG was discussed.