Self - Assembly Behavior And Morphology Of Organic Small Molecule Gels In Response To Environmental Stimulation

Organogel can organize into regular nano-architectures through specific non-covalent interactions including hydrogen bonds, π-π interactions, hydrophobic interactions, and van der waals forces to make the whole system into gel. As a new kind of smart soft materials, more and more people were interesting in it. Because of low weight mass organogel had unique properties responsive to external environmental stimulation, the diversity of morphology formed by collaboration and competition through a variety of weak interactions between molecules. These kinds of materials could be used into drug delivery, cell culture, templates of inorganic nanomaterials and so on. In this thesis, three kinds of gelator were designed and synthesized. The change of the gel formation mechanism, the microscopic morphology and the molecular packing fashion under the external environment stimulation were studied in detail. The whole paper contains four parts as following:1. Formation of a large-scale ordered honeycomb pattern1) We designed and synthesized a novel gelator with cholesteryl group and adamantyl group on two sides of the molecule linked by two amide bonds and a naphthalimide group. Spatially-ordered structure with high surface area was formed by the effect of self-assembly.2) The gelator could make many kinds of solvent into gel with different morphologies. Orderly patterned honeycomb nanostructure was obtained in dichloromethane. We proposed a hypothesis that the honeycomb nanostructure was evolved from hollow vesicle structures.2. Morphological transformation between three-dimensional gel network and spherical vesicles via sonication1) Based on the work of part1, naphthalimide group was removed. The self-assembly morphology of the molecule could be manipulated through the effect of ultrasound and heating-cooling.2) The gelator couldn’t make the ethanol solvent into gel on the concentration of20mg/mL. After heating and cooling, white turbid precipitate was formed with hollow vesicle morphology. When the solution was heated and treated with ultrasound, it was changed into gel with three dimensional network structures.3) The formation mechanism of the hollow vesicle structures and three dimensional network structures was studied. We proposed that ultrasound has some effect on molecular packing.3. Morphology evolution from nano ribbon, ordered nano thread to vesicle via manipulation of the self-assembly between an adamantine based gelator and cyclodextrin1) Based on the supramolecular interaction between cyclodextrin and adamantine, we introduced cyclodextrin into the gel system containing adamantine. The morphology was changed from nano ribbon to ordered nano thread by addition of cyclodextrin. The nanowires were orderly arranged in parallel with the width of about25nm. The largest ratio of length and width was about1000:1. With the further addition of water, the ordered nano thread was changed to nanotubes and nano vesicles. Thus a simple method was achieved for preparation different morphologies of nano materials such as nano ribbons, ordered nano thread, nanotubes and nano vesicles in the same system by adjustment of the self-assembly process.2) The mechanism study proved that the intermolecular interaction between gelator and CD as well as the hydrophobic cavity of CD were the main driving force for the evolution of the morphologies.4. From Nano Ribbon to Fiber by Concentration Control1) A molecule with fluorene in one side and tert-butyl in the other side linked by hydrophilic carbamate enthylenediamine was designed and synthesized. The molecule can gelate several kinds of solvent. One dimension spatially ordered structure was formed by self-assembly of the molecule via gelation.2) By regulation of the concentration, the morphology of the gel was changed from nano ribbon to fiber. The ratio of the length and diameter of fiber was extremely high. The nanowires have layered structure packing model.