【作者】 王宁霞；

【导师】 杨亚江；

【作者基本信息】 华中科技大学 ， 高分子化学与物理， 2007， 硕士

【摘要】 某些小分子有机化合物能在很低的浓度下(甚至低于1wt%)使大多数有机溶剂凝胶化,进而使整个体系形成类似粘弹性液体或固体的物质,称为超分子凝胶或超分子有机凝胶。这类小分子化合物被称为Gelator (暂译为凝胶因子)。特别地,如果凝胶因子能使水发生凝胶化,则称所形成的凝胶为超分子水凝胶。这类超分子凝胶是通过凝胶因子分子间氢键、π-π键、疏水力和范德华力等非共价键相互作用,在溶剂中自发地聚集、自组装成有序结构,进而使整个体系凝胶化而形成的物理凝胶,具有三维网络结构。本文通过分子设计,将酰胺基和长链烷烃及吡啶引入到L-苯丙氨酸分子中,成功地合成了水性凝胶因子NP18PB,这种L-苯丙氨酸衍生物凝胶因子在很低的浓度(1wt%)下使水发生凝胶化。FTIR、稳态荧光光谱和XRD研究发现,凝胶因子NP18PB是通过分子间氢键和烷烃链的疏水作用力而聚集、自组装形成超分子水凝胶的。通过偏光显微镜(POM)、场发射扫描电镜(FE-SEM)研究发现NP18PB在水中自组装形成纤维状的聚集体。以凝胶因子TC18PheBu在水中的自组装聚集体为模板,以钛酸四丁酯为钛源,钛酸四丁酯吸附在聚集体模板表面,通过溶胶-凝胶缩聚,然后经过高温煅烧得到了项链型的TiO2纳米线。利用场发射扫描电镜(FE-SEM)、X射线衍射(XRD)以及傅立叶红外光谱(FTIR)对所制备的项链型TiO2纳米粒进行表征,从而对项链型TiO2纳米粒的形成机理进行了合理解释。在TC18PheBu-TiO2中形成的纳米线是通过钛酸四丁酯水解形成的带负电的低聚物与季铵盐正离子的静电作用形成的。更多还原

【Abstract】 Many solvents can be gelated by some compounds of low molecular weight at low concentrations (typically <1wt %) and form thermally-reversible viscoelastic liquidlike or solidlike materials that are called supramolecular gels or supramolecular organogels. Such low molecular-weight compounds are called“gelator”. The hydrogels forms when the water is gelated. The gelators can self-assemble into nanoscale superstructures through hydrogen bonding,π-πstacking, van der Waals, hydrophobic interactions to create three-dimensional networks.This paper presents novel L-phenylalanine derived hydrogelators NP18PB. The hydrogelator can make water gelated at a low concentration. It is found that hydrogen bonding and hydrophobic interactions play an important role on the formation of supramolecular hydrogel by FTIR, Fluorescence Spectrum and XRD. FE-SEM and POM showed that NP18PB self-assembled into fiber-like aggregates in the water.Using the fiber-like aggregates assembled by another hydrogelator TC18PheBu in water as templates, tetrabutyl titanate as precursors, tetrabutyl titanate adsorbed onto the surfaces of fiber-like aggregates, and then polymerized by sol-gel polymerization, Pearl-necklace-like TiO2 nanowires formed after calcinations. The possible mechanism of the formation of the Pearl-necklace-like TiO2 nanowires was discussed by FE-SEM, XRD and FTIR. The electrostatic interaction between cationic gelator and anionic metal oxide precursor plays an important role in the transferring process.更多还原