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采用开环聚合、发散法以及“点击化学法”合成了线型-树状聚两性电解质.首先通过γ-苄基-L-谷氨酸酯羧酸酐(BLG-NCA)的开环聚合及发散合成法分别合成了叠氮端基聚(γ-苄基-L-谷氨酸酯)(PBLG-N3)及以炔基为内核的带有4个伯氨端基的第2.0代聚酰胺-胺(PAMAM-D2),再将二者通过“点击反应”制备的线型-树状嵌段共聚物PBLG-b-D2作为大分子引发剂,利用其末端氨基引发ε-苄氧羰基-L-赖氨酸羧酸酐(ZLL-NCA)的开环聚合,获得线型-树状嵌段共聚物PBLG-b-D2-(PZLL)4,再经酸解脱除PBLG上的苄基及PZLL上的苄氧羰基,获得目标产物聚(L-谷氨酸)-b-聚[酰胺-胺-聚(L-赖氨酸)](PLGA50-b-D2-(PLL9)4)线型-树状聚两性电解质.通过核磁(1H-NMR)、傅里叶变换红外光谱(FTIR)和凝胶渗透色谱(GPC)表征了聚合物分子结构、分子量及其分布;通过电导滴定法、1H-NMR、zeta电位、激光光散射(LLS)、扫描电子显微镜(SEM)及圆二色谱(CD)等方法研究了PLGA50-b-D2-(PLL9)4对溶液pH值响应性.结果表明随溶液pH由酸性转变为碱性,PLGA50-b-D2-(PLL9)4显示出了多重胶束化行为,同时不对称的线型-树状分子拓扑结构影响了聚集体的形貌,在酸性pH值下形成以PLGA为核的球形胶束,而在碱性pH值下形成以PLL为核的棒状胶束,并分别伴随着PLGA及PLL链段构象从无规线团向螺旋构象的转变.
The linear-dendritic polyelectrolytes were synthesized by the ring-opening polymerization, the divergence method and the “click-chemistry method.” First, the ring-opening polymerization of γ-benzyl-L-glutamate carboxylic anhydride (BLG-NCA) (Γ-benzyl-L-glutamate) (PBLG-N3) and the second generation of poly Amide-amine (PAMAM-D2), and then both the linear-dendritic block copolymer PBLG-b-D2 prepared by “click reaction ” was used as a macroinitiator, Ring-opening polymerization of oxycarbonyl-L-lysine carboxylic acid anhydride (ZLL-NCA) to obtain linear-dendritic block copolymer PBLG-b-D2- (PZLL) 4, (L-lysine)] (PLGA50-b-D2- (PLL9) 4) to obtain the target product poly (L-glutamic acid) Linear-dendrimeric amphoteric electrolytes were synthesized and characterized by 1H-NMR, FTIR and GPC. The molecular structures, molecular weights and their distributions were characterized by conductometric titration , 1H-NMR, zeta potential, laser light scattering (LLS), scanning electron microscopy (SEM) The results of PLGA50-b-D2- (PLL9) 4 pH response to solution showed that PLGA50-b-D2- (PLL9) 4 showed a Multiple micellarization behavior with asymmetric linear - dendrimer topography affects the morphology of the aggregates, forming spherical micelles with PLGA as nucleus at acidic pH and forming PLL as the core of the rod-like micelles, and accompanied by the PLGA and PLL conformation from the random coil to the spiral conformation.