【作者】 李伟娜；

【导师】 巨勇； 李广涛；

【作者基本信息】 清华大学 ， 化学， 2013， 博士

【摘要】 胆甾酸是一类来源于生物体的化合物，具有微凹的刚性骨架和面式两亲性，在高分子和超分子化学界引起了广泛的关注。到目前为止，关于胆甾酸主链型高分子的制备仍然具有极大的挑战性，胆甾酸刚性骨架及其独特的两亲性特征在超分子组装中的作用仍未被详细报道。本论文以胆甾酸分子为构筑基元，充分利用其独特的结构特征，设计合成了一系列胆甾酸主链型高分子，研究了它们的超分子组装、多级组装和褶皱现象，取得了以下研究成果：设计合成了一系列含末端炔基和叠氮反应基团的胆甾酸衍生物。利用胆甾酸刚性骨架和面式两亲性，通过结晶方法，得到三种化合物的单晶结构。在胆甾骨架预组织排列作用下，炔基和叠氮在晶体内部交错平行排列。利用拓扑化学聚合法，无金属催化剂和有机溶剂存在下，炔基和叠氮在晶体内部快速高效聚合，得到高分子量的胆甾酸主链型高分子，且单体转化率达到100%，产物无需进一步的后处理。与非晶体状态和溶液相反应的结果相比，分子量高1-2个数量级，反应效率也得到极大提高。在晶体结构的空间限域作用下，无催化剂条件下的1,4-位三唑的区域选择性也有一定的提高。对具有良好生物相容性的胆酸主链型高分子的超分子组装进行研究，探讨了胆酸独特骨架及面式两亲性在超分子组装中的作用及其赋予组装体的独特性质。发现胆酸骨架在超分子组装中起支撑作用，通过亲/疏水面的氢键作用和疏水骨架堆积形成单分散的稳定囊泡结构。依托胆酸两亲性特征，赋予高分子囊泡良好的自适应性，并具有可逆调节的特点。基于胆酸微凹刚性骨架，在囊泡壁中构筑一系列动态可调的亲/疏水微腔。在囊泡壁中引入了三唑基团，使囊泡壁的透过性具有酸碱可控和可逆调节的特性。合成区域选择性的1,4-三唑连接的胆酸主链型生物高分子，研究其多级组装过程以及褶皱现象。胆酸主链型高分子在极性溶剂诱导下，首先形成具有一维亲水空腔的折叠结构，通过疏水骨架堆积进一步组装产生层状薄膜。在胆酸骨架和面式两亲性调控的多级有序组装结构以及物理组装共同作用下，超分子薄膜自发形成大面积有序褶皱。首次通过化学的超分子多级组装和物理组装过程，得到生物高分子有序褶皱，同时加深了对胆甾骨架及面式两亲性在组装中作用的认识。更多还原

【Abstract】 The natural occurring bile acids with the curved rigid steroidal skeleton anddistinctive facial amphiphilicity have attracted great attentions in polymer chemistry andsupramolecular chemistry. Until now, the preparation of high molecular weight mainchain bile acid polymers is still a great challenge. The supramolecular functionalmechanisms of bile aicd polymers, which are controlled by the unique steroidal skeletonand facially amphiphilic properties, is still in its infancy. In this dissertation, based onthe bile acid building blocks and their unique structures, we design and synthesis aseries of main chain bile acid polymers and focused on their supramolecular assembly,multi-level hierarchical assembly as well as the wrinkle phenomenon. The major workis as follow:A series of bile acid derivatives with terminal alkyne and azide reaction groupshave been synthesized. Due to their rigid steroidal skeleton and facial amphiphilicity,the single crystals of three compounds were obtained by crystallization. The alkyne andazide groups are paralleled to each other in the crystal lattice. By topochemicalpolymerization, the high molecular weight main chain bile acid polymers were obtainedin the absense of metal catalysts and the organic solvents. With the advantages of100%monomers conversion, the polymerization of the alkyne and azide groups occurred inthe crystal lattice and the resulted polymers don’t need further purification. Comparedwith the polymerization process in the amorphous solid state and solution phase, thereaction efficiency and the molecular weight as well as the selectivity of the1,4-triazolegroups were greatly improved.The supramolecular assembly behavior of main chain cholic acidbiopolymers was studied. Depending on the unique rigid skeleton and facialamphiphilicity, the supramolecular assemblies were characterized by thevesicles stability, adaptability and reversible adjustment as well as the uniquehydrophilic and hydrophobic binding pockets in the vesicle membranes. Due tothe presence of triazole groups in the polymer chains, the permeability of thevesicle membrane was response to the pH changes and this process is reversiblefor several cycles. The main chain cholic acid polymers with regioselective1,4-triazolegroups as linkages were synthesized and their multi-level hierarchical assemblyas well al wrinkling phenomenon were developed. Induced by the polar solvents,the folded structures with one-dimensional hydrophilic cavity were firstlyformed and then stacked together leading to the multi-lamellar membraneassemblies. Based on the multi-level ordered assembly structures, which werecontrolled by the rigid steroidal skeleton and their unique facial amphiphilicity,and the physical assembly process, the large scale ordered wrinkles wereobtained. By combination of supramolecular multi-level assembly and physicalassembly, the biopolymer wrinkels with the potential applications in the celladhesion were developed.更多还原