具有刚性液晶元侧基的嵌段共聚物PHEMAChol-b-PBLG的合成及自组装研究  

Preparation and Self-assembly of PHEMAChol-b-PBLG Diblock Copolymers Bearing Rigid Liquid Crystal Cholesterol Grafts

作　　者：王昭[1] 罗志基 李明睿[1] 盛瑞隆[1] 罗挺[1] 曹阿民[1] 

机构地区：[1]中国科学院上海有机化学研究所中国科学院有机功能分子合成与组装化学重点实验室,上海200032

出　　处：《高分子学报》2016年第5期667-678,共12页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21174160;21372251)资助项目

摘　　要：以胆固醇和谷氨酸苄酯为主要出发原料,采用可逆加成-断裂链转移(RAFT)自由基聚合、氨基酸环内酸酐(NCA)开环聚合(ROP)以及"点击化学"(click chemistry)组合方法,设计、合成了系列具有刚性液晶元侧基的聚甲基丙烯酸羟乙酯胆固醇碳酸酯-嵌段-聚谷氨酸苄酯(PHEMAChol-b-PBLG),并通过核磁共振(NMR)、红外光谱(FTIR)、凝胶渗透色谱(GPC)和静态光散射(SLS)对其化学结构进行了表征.运用热重分析仪(TGA)、热台偏光显微镜(POM)和示差扫描量热仪(DSC)研究了系列共聚物的热稳定性、液晶相结构及相转变行为,并通过固体红外、13C固体核磁共振(13C CP/MAS)和X射线衍射仪(XRD)研究了PBLG均聚物及系列嵌段共聚物中聚氨基酸多肽链段的二级结构.研究结果表明,系列嵌段共聚物均具有良好的热稳定性,表现为近似向列相的液晶织构,PBLG链段趋于呈刚直棒状的α-螺旋构型,且其多肽链段越长,二级结构越规整.进一步采用圆二色谱(CD)和透射电镜(TEM)对系列嵌段共聚物在四氢呋喃溶液中的二级结构及自组装行为进行了研究,制备得到纺锤形自组装聚集体和大复合胶束,并通过变性酸三氟乙酸的引入实现对嵌段共聚物中PBLG的二级结构及相应自组装聚集体形貌的有效调控.A series of new diblock copolymers bearing rigid liquid crystal cholesterol grafts denoted as PHEMAChol-b-PBLG were designed and sucessfully prepared via a combination of reversible additionfragmentation chain transfer polymerization（ RAFT）,ring opening polymerization（ ROP） and ＂click ＂chemistry,and their molecular structures were further characterized by NMR,FTIR,GPC and static light scattering（ SLS）. Then,liquid crystal（ LC） phase structures and their transitions as well as thermal stabilities were characterized by differential scanning calorimetry（ DSC）,polarized optical microscopy（ POM） and thermo gravimetric analysis（ TGA）,and secondary structures of the PBLG blocks were analyzed by FTIR,Xray diffraction（ XRD） and solid-state13 C CP / MAS NMR techniques. Moreover,their secondary molecular structures in THF were analyzed by circular dichroism spectrum（ CD）,and self-aggregate morphologies in THF / DMF mixed solution were investigated by transmission electron microscopy（ TEM）. The results demonstrated predominant α-helix secondary structures of PBLG blocks for the resulted PHEMAChol-b-PBLG in solid state,and the longer PBLG blocks led to more well-defined α-helix structures,and PBLG secondary structures in solution could be tuned by their block lengths and the TFA volume fraction.

关 键 词：二嵌段共聚物 胆固醇液晶元 聚谷氨酸苄酯 大分子二级结构 自组装 

分 类 号：O631.5[理学—高分子化学]