接枝改性POSS对PLLA结晶行为的影响*

以二氯甲烷为溶剂,利用溶液共混法将三种聚笼形多面体倍半硅氧烷(POSS)分别与聚左旋乳酸(PLLA)进行共混,制备了不同POSS含量的单氨基POSS(POSS-NH₂)/PLLA、POSS接枝聚乙二醇(POSS-PEG)/PLLA和POSS接枝聚乳酸(POSS-g-PLLA)/PLLA复合材料。利用差示扫描量热仪(DSC)、热重分析仪(TGA)、偏光显微镜(POM) 分别对复合材料的本体结晶行为、热稳定性及结晶形貌和生长速率进行了观察。结果表明当加入不同质量分数(1 wt%, 5 wt%, 10 wt%)的POSS-PEG时,PLLA的结晶能力均得到改善,而POSS-NH2和POSS-g-PLLA仅在质量分数较低(1wt%)时对PLLA起成核剂的作用,具有较高质量分数时会阻碍PLLA分子链段的运动,从而限制其结晶。三种复合材料中仅POSS-PEG在一定程度上提高了PLLA的热稳定性,利用POM观察球晶生长过程发现POSS-PEG的加入提高了PLLA的球晶生长速率。

Effect of Graft Modified POSS on the Crystallization behavior of PLLA

The Aminopropyllsobutyl Polyhedral oligomeric silsesquioxane (POSS-NH₂), POSS grafted polyethylene glycol (POSS-PEG) and POSS grafted poly(lactic acid) (POSS-g-PLLA) were blended with poly(L-lactic acid)(PLLA) by solution blending method in dichloromethane, then the POSS-NH₂/PLLA, POSS-PEG/PLLA and POSS-g-PLLA/PLLA composites with different mass fraction of POSS were obtained. The Differential scanning calorimetry (DSC), Thermogravimetric Analysis (TGA), and Differential Polarizing Microscope (POM) were used to investigate the crystallization behavior in bulk, the thermal stability, the crystallization morphology and the growth rate of composites, respectively. The results show that the crystallization ability of PLLA is improved by the adding of POSS-PEG with mass percentage of 1 wt. %, 5 wt. % and 10 wt. %. However, POSS-NH₂ and POSS-g-PLLA will depress the crystallization ability of PLLA when the POSS have larger mass contents (5 wt. % and 10 wt. %). Based on the TGA results, it can be known that the POSS-PEG improves the thermal stability of PLLA slightly. Based on the POM observation, it can be found that addition of POSS-PEG promotes the spherulite growth rate of PLLA.