【作者】 侯秋飞；

【导师】 姜世梅；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2010， 博士

【摘要】 近年来,对于分子凝胶及其自组装纤维网络的研究日益引起人们的重视,随着已报道的凝胶因子的数目越来越多,人们对分子凝胶的研究已经不再满足于发现新的凝胶因子,如何赋予凝胶因子更多的功能性并开发其凝胶的潜在应用价值已经成为现阶段的主要研究热点。我们选用结构特点较为明显的三烷氧基苯甲酰和胆固醇衍生物凝胶体系,结合本组在刺激响应方面的研究经验,尝试把一些具有多重刺激响应性的功能基团引入到凝胶体系,以构筑具有多重刺激响应性的凝胶软材料。本论文围绕上述思想开展了如下工作:首先,设计合成了四个结构对称的三烷氧基苯甲酰胺衍生物,考察了它们对于不同溶剂选择性形成凝胶的能力,并用相图对形成的凝胶进行了表征。综合运用SEM、FTIR、XRD等技术手段对凝胶因子的自组装结构进行了详细研究,分析讨论了凝胶因子的分子结构与凝胶性能的关系。其次,设计合成了五个基于双水杨醛西佛碱的A(LS)2型胆固醇衍生物,凝胶测试发现其中的一个化合物可以在等体积的甲苯和醇混合溶剂中形成稳定的凝胶,凝胶既可以通过传统的热诱导的方法获得,也可以通过超声辅助的溶剂诱导的方法得到,这是一种新的分子凝胶的形成方法。我们运用各种研究手段比较了两种条件下形成的凝胶在宏观性能和微观自组装结构上的差异。另外,凝胶自组装结构还表现出很好的离子响应特性。然后,设计合成了一种基于苯乙烯基吡啶的ALS型胆固醇衍生物,其具有对光和质子的双重可逆刺激响应性质,可以设计成多种双输入的分子逻辑门。虽然这个化合物在各种测试溶剂中都不能形成凝胶,但其基于非共价相互作用形成的氢键复合物和掺杂复合物却表现出很好的凝胶性能。氢键复合物除可以自组装形成凝胶外,还表现出明显的热致液晶行为。掺杂复合物形成的凝胶具有显著的层状结构,并且其形貌表现出对掺杂比例的依赖性。利用超分子的掺杂复合等手段构筑凝胶因子在文献中鲜有报道,这为凝胶因子的设计合成开辟了一个新的思路。更多还原

【Abstract】 In recent years, there has been immense interest in studying molecular gels and their self-assembled fibrillar networks (SAFINs). As the number of the reported low-molecular-mass gelators is growing, the study of molecular gels is no longer only focused on the discovery of new gelators. The design and synthesis of gelators with more functional groups and the development of their potential applications have become the major research focuses at the present stage. We choose the widely used trialkoxybenzoyl- and cholesterol-based molecular gel systems. According to the research experience for the stimuli-responsive molecules in our group, we try to introduce some stimuli-responsive molecules into the gelator systems, and build new soft materials with multiple stimuli-responsive properties. Based on the above ideas, we have carried out some work as follows:Firstly, we designed and synthesized four trialkoxybenzoyl-based molecules with similar symmetrical structures, and studied the structure-property relationship of these molecules. It was found that the para-substituted derivatives of p-phenylenediamine and benzidine could form stable gel in many organic solvents, while the meta-substituted derivative of m-phenylenediamine could only form gel in ethyl acetate and n-propanol, and the ortho-substituted derivative of o-phenylenediamine even could not form gel in any test solvents. The formed gels were studied by phase diagrams, SEM, FTIR, XRD, and the main effects of intermolecular hydrogen bonds and van der Waals forces on the self-assembly of gelators into SAFINs were analyzed and discussed.Secondly, we designed and synthesized five A(LS)2-type cholesterol derivatives centered with salen-type bis-salicylaldehyde Schiff-base functional units. After studying the gelability of these molecules in different solvents, we found that only compound G1 was a good gelator. G1 can form a stable gel with volume ratio of 1:1 toluene/alcohol mixed solvent at a very low concentration. The microstructure of the gel was studied by SEM, FTIR and XRD, and it was found that the intermolecular hydrogen bonds, van der Waals forces and the possibleπ-πinteractions played a key role in the self-assembly of the gelator. In addition, we found that G1-gel could be formed either through the traditional thermal-induced method, or under the influence of ultrasound. By exactly examining the gels formed with these two methods, we found that the second method was not the ultrasound-induced gelation as reported in the literature, and in nature, it was the ultrasound-assisted solvent-induced gelation and which was a new gel-forming method. Finally, we also tested the ionic sensitivity of G1 and its gel. G1 was sensitive with many transition metal ions, such as Zn2+, Cu2+, Cd2+, Pb2+ and Hg2+, and some anions, such as OH- and CN-, accompanying with clear spectra and color change. Such a response at the molecular level could be well transcribed to the gel, and G1 gel sould respond to these ions with a gel-to-sol transition, and these responses were quantitative in some degree. These properties might endow G1 and its gel with potential applications as indicator or adsorbent for toxic ions, and the results also confirmed that the intermolecular hydrogen bond plays a key role in the gel formation.And then, we designed and synthesized a stilbazole-based ALS-type cholesterol derivative G6, which showed good stimuli-responsive properties. It could perform photoisomerization and protonation with UV light and HCl, respectively. By choosing the suitable photostationary state as the starting state, and the UV light and HCl as two inputs, we had constructed five two-input logic gates and a 1:2 demultiplexer. But it was found that G6 could not form gel in any test solvents, and showed a certain degree of crystallization. We tried some methods to inhibit the crystallization, and achieved some success. First, we found the 1:1 hydrogen-bonding complex of G6 could form stable gel in some solvents, and the formed gel was characterized in detail. In addition, the hydrogen-bonding complex showed thermotropic mesomorphic behavior. Then, we found that G6 could also form gel with the doping of a A (LS)2-type molecule, and the quantity of the dopant could affect the gel formation and the morphology of formed gel. The effect of the structure of the dopant on the gel formation was discussed, and this might make a new way for the design and synthesis of gelators.更多还原