以不同臂数和分子量的星型聚乙二醇（sPEG）和L-丙交酯为原料,采用开环聚合法合成了以星型聚乙二醇为内部嵌段、聚L-乳酸为外部嵌段的多臂星形聚乙二醇-聚乳酸嵌段共聚物（sPEG-b-PLLA）。研究了sPEG的臂数、分子量及L-丙交酯/sPEG投料比等参数对产物结构与性能的影响。并分别用红外光谱（FT-IR）、核磁共振（1H-NMR）、凝胶渗透色谱（GPC）、差示扫描量热（DSC）对产物进行了表征,证实所合成的嵌段共聚物具有预期的结构。结果表明,sPEG-b-PLLA为结晶性聚合物,且表现出与PLLA相似的晶型,随着PLLA链段的增加,产物的结晶度也呈增大的趋势;与PLLA相比,sPEG-b-PLLA的接触角随着PEG链段的增多而增大,表明其亲水性明显改善。
Biodegradable,amphiphilic,diblock multi-arm star-shaped poly（ethylene glycol）-block-poly（L-lactide） copolymer（sPEG-b-PLLA） were prepared by ring-opening polymerization of L-lactide in the presence of multi-arm sPEG and a catalytic amount of stannous octoate,in which three types of sPEG,i.e.,sPEG1（4-arm,n=4300）,sPEG2（3-arm,n=3200） and sPEG3（4-arm,n=12400） were chosen as the core of the block copolymer.The polymers,including sPEG and sPEG-b-PLLA copolymers with varied core and varied lactide/sPEG ratios were characterized and confirmed by 1H nuclear magnetic resonance spectrum（1H-NMR）,Fourier transform infrared spectrum（FT-IR） and gel permeation in chromatography（GPC）.The results showed that a serial of sPEG-b-PLLA copolymers with expected structures are successfully prepared.X-ray diffraction（XRD） results show that the sPEG-b-PLLA copolymers have similar crystal structure as that of PLLA,and its crystallinity is improved with the increase of PLLA segments.Contact angle testing shows that compared with linear PLLA,the hydrophilic properties of sPEG-b-PLLA are distinctly improved with the increase of PEG segments.
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