Molecular Design Of Polymerizable Amphiphiles And Manufacture Of Nanostructured Polymeric Materials

In chapter one of this thesis we gave at first a concise summary of the phase behavior of surfactants, the microstructures of major surfactant phases and the physical means for elucidation of the phase microstructures. Then progresses in manufacturing nano-structured polymeric materials via immobilization of the phase structures were introduced with detailed description of the systematic work of three major researchers in the field: Gan L.M., Gin D.L. and O'Brien D.F.. With the knowledge accumulated in their exploration we developed our points of research and set the goal of formulating and immobilizing surfactant phases of more diversified compositions.In chapter two we synthesized four linear-chain polymerizable amphiphiles. Study of their ternary phase behavior showed that only isotropic solution phases appeared in their partial ternary phase diagrams. The introduction of polymerizable acrylate groups was believed to reduce the amphiphilicity of the molecules. Polymeric materials of various microstructures could be manufactured through polymerization of the isotropic solution phases, in which many factors played different roles. Polymerization of the acrylate group located near the hydrophilic head could bring more distortion to the phase structure than polymerization of the acrylate group far from the head. High contents of water in the phases made the phases more vulnerable for immobilization. High content of crosslinker in the oil phase gave better immobilization, but too high content of oil in the total phase brought significant heterogeneity to the polymeric materials.In chapter three we reported design and synthesis of a group of polymerizable amphiphiles with systematically varied structures. The design was modular, flexible and extendable. The synthesis was optimized to give satisfying yields and purities. A general procedure of recrystallization in nitrogen atmosphere and at low temperature was devised to facilitate purification of the final amphiphiles, most of which are highly hygroscopic, too polar to be eluted on silica gel column and highly polymerizable. Studies of their ternary phase behavior showed that the structural symmetry of both the hydrophilic and the hydrophobic modules was critical for the formation of homogeneous phases. The liquid crystallinity of the amphiphiles could be understood well with Israelachvili's geometrical model of micelles, confirming thevalidity of our modular molecular design. The immobilization of the liquid crystalline phases with photopolymerization was studied with small angle X-ray scattering and polarized light microscopy. Generally hexagonal phases could be immobilized well, although the structural order was reduced to various extents. But the cubic phases could evolve with polymerization to another structural pattern which was close to a lamellar structure with the basic length of 110～140A|°. Both the order reduction of hexagonal phases and the structure evolution of cubic phases were believed to be based on the same microscopic mechanism, which need more experimental facts to be elucidated. On the whole the work in this chapter provided a molecular design scheme effective in achieving molecular diversity of polymerizable amphiphiles and succeeded in manufacturing a series of nanostructured polymeric materials with long-range order.In the last chapter we summarized the major work of this thesis and proposed that the future work in the study of manufacturing nanostructured polymeric materials via immobilization of surfactant phases could be focused on two points: design of much larger polymerizable amphiphiles with specific molecular interactions and much more effective structural characterization to trace the evolution of phase microstructures with polymerization.