Fabrication And Self-assembly Of Supra-amphiphiles With Different Topologies

Supra-amphiphile refers to the amphiphile formed by intermolecular interactions. It is not only a new bridge between supramolecular chemistry and surface & colloid chemistry, but also an important method to realize controllable self-assembly. The topological structure of supra-amphiphiles influences their properties in bulky phase and interface greatly. In this thesis, we have developed supra-amphiphiles with different topologies by using dynamic covalent bonds and host-guest interactions. Their selfassemblies in aqueous solution and behaviors on interface are also carefully investigated. Meanwhile, we have demonstrated that the self-assemblies of the supraamphiphiles will affect their intermolecular interactions significant ly. Our work includes four parts as follows:1. Imine bond, which is the most common dynamic covalent bond, is used to fabricate a bolaform supra-amphiphile. Its pH-responsive self-assembly in water are investigated. Furthermore, controlled release of guest molecules can be realized by its pH-responsiveness. The rate of the controlled release depends on the pH of the solution.2. On the basis of the above work, we fabricate a series of bolaform supraamphiphiles with different symmetries by using the imine bond. Their self-assemlies and equilibriums of imine are significantly different. A good symmetry always leads a higher conversion of the building blocks. Thus it can be seen that the topology of the supra-amphiphile will not only affects their aggregation, but also the formation and dissociation of the intermolecular interaction.3. A series of supra-amphiphile with more complex topological structure, which is named H-shaped supra-amphiphiles, are also fabricated by using imine bond. The critical micelle concentration of the H-shaped supra-amphiphiles are quite low. Their imine bonds are more difficult to be hydrolyzed by acid. These features become more significant when the alkyl chain gets longer. The reason should be that the hydrophobic core of the aggregation protects the imine bonds from being hydrolyzed. The protection shows the influence of self-assembly to the intermolecular interactions, again. Furthermore, the surface activity of the H-shaped supra-amphiphile is investigated, too.4. The host-guest interaction based on cucurbituril is used to tune the surface activity of a gemini amphiphile. The surface tension, wetting, foaming and emulsifying ability of the gemini amphiphile change significantly after the alkyl chains of gemini amphiphile are bound with cucurbituril. The surface activity will recover if a guest molecle that has a better binding ability with cucurbituril is added. The reversible, quick and repetitive tuning of the surface activity can be realized by adding the cucurbituril and competitor alternatively.