氧化石墨烯接枝聚乙二醇对左旋聚乳酸结晶行为和热稳定性的影响

为改善聚乳酸的结晶性能和热稳定性，通过酯化反应将聚乙二醇(PEG)接枝到氧化石墨烯(GO)表面，制备出表面修饰PEG的GO(GO-g-PEG)作为聚乳酸的结晶促进剂。利用溶液共混法制备出不同GO-g-PEG含量的GO-g-PEG/左旋聚乳酸(PLLA)复合材料，通过傅里叶变换红外光谱仪(FTIR)和X射线衍射仪(XRD)表征分析证实PEG成功接枝到GO表面。通过差示扫描热量仪(DSC)、热台偏光显微镜(POM)和热重分析仪(TGA)研究GO-g-PEG对PLLA结晶行为和热稳定性的影响。结果表明：在GO-g-PEG的异相成核及增塑作用下，GO-g-PEG/PLLA复合材料结晶成核密度明显增大，结晶能力和结晶度提高；在PEG接枝量为11.8%(质量分数)时，GO-g-PEG/PLLA复合材料的热分解温度较纯PLLA提高20 ℃左右。

Effects of graphene oxide grafted polyethylene glycol on crystallization behavior and thermal stability of poly(L-lactic acid)

In order to improve the crystallization properties of polylactic acid, the crystallization accelerator of graphene oxide grafted polyethylene glycol (GO-g-PEG) was prepared by esterification. The GO-g-PEG/poly(L-lactic acid) (PLLA) composite materials with different GO-g-PEG contents were prepared by solution blending method, and the structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD). The effect of GO-g-PEG on the crystallization behavior and thermal stability of PLLA was studied by differential scanning calorimeter (DSC), polarizing microscope (POM) and thermogravimetric analyzer (TGA). The results show that under the heterogeneous nucleation and plasticization of GO-g-PEG, the crystallization nucleation density of GO-g-PEG/PLLA composites is increased significantly, the crystallization ability and crystallinity are improved; when the grafting amount of PEG is 11.8%(mass fraction), comparing the thermal stability of GO-g-PEG/PLLA composites with PLLA neat, the thermal decomposition temperature of GO-g-PEG/PLLA composites is increased by about 20 ℃.