含顺反异构双胆固醇型小分子胶凝剂的合成与胶凝行为

摘要

以甘氨酸为连接臂、顺反丁烯二酸为功能基团设计合成了2种具有不同立体异构连接臂的A(LS)2 型双胆固醇类小分子胶凝剂MA-C和FA-C.考察了MA-C和FA-C对30种常见有机溶剂的胶凝能力.结果表明,MA-C和FA-C的胶凝能力及其所形成凝胶的性质依赖于胶凝剂分子的立体异构.特别是MA-C能使CCl4室温胶凝,而且所形成凝胶具有良好的热稳定性和显著的剪切触变性.另外,此胶凝剂还能在H2O/CCl4混合体系中选择胶凝有机相.显微分析表明,凝胶中胶凝剂聚集体的形貌不仅依赖干胶凝剂分子的立体异构和胶凝剂的浓度,而且与胶凝剂分子与溶剂分子间的相互作用有关.变温、变浓度的'H NMR研究表明,胶凝剂分子间的π-π堆积和氢键作用是凝胶形成的重要驱动力.此外,根据XRD和其它实验结果提出了MA-C在CCl4中的可能堆积模型.%Two cholesterol-containing low molecular mass gelators ( LMMGs ) of A ( LS ) 2 type with glycin in the linkers and butene diacid in the A part were prepared. Their gelation abilities were evaluated in 30 commonly used organic solvents. It was found that the change in the stereo-structure of the linker had a dramatic effect upon the gelation behaviors of the gelators. Interestingly, MA-G gelated CC14 spontaneously at room temperature, and the gel as-formed exhibited good thermal stability and thixotropic property as revealed by rheo-- logical studies. More interestingly, MA-C showed phase-selective gelation of CC14 from its mixture with water. SEM observation demonstrated that the morphologies of the aggregates of the gelators in the gels depend, but not only, on the structures of the gelators. The concentrations of the gelators, and even their interactions with the solvents also showed great effect upon the morphologies. Temperature and concentration dependent 1H NMR measurements revealed that inter-molecular hydrogen bonding and π-π stacking among the molecules of the gelators are important driving forces for the formation of the gels. XRD study revealed that MA-C assembled into a layered structure in its CC14 gel.