Organic-inorganic hybrid nanocomposites for the investigation of structure-function relations in porous materials.

Abstract

Depending on the type of the pore structure, porous materials manufactured through various methods of synthesis are generally used in gas storage, gas adsorption-desorption, chemical separation process and removal of pollutants from the water purification process. However, despite being one of the oldest research topics, porous structures still have infinite possibilities and shortcomings. Therefore, this thesis focuses on the improvement and development of the widely known porous particles. For the study, MOF (Metal Organic Framework) and MC (Mesoporous Carbon structure) were selected as research target materials which are obtained by the fusion complex of organic and inorganic materials. Because those structures were synthesized by new route, unlike traditional porous nanomaterials. The first chapter of the thesis introduces the characteristics and classifications of organic-inorganic hybrid and porous materials. Since porous materials have been studied for a long time and numerous models exists, the types of porous materials and their applications depending on their pore size were evaluated.In the second chapter, a surface modification process is introduced. Using 4-tertbutyl calix[n]arene monomer coated on the UIO-66 (a well known MOF structure), the hydrophilic surface of MOF could be converted to hydrophobic. Since most of MOF structures demonstrate hydrophilic surface property, it is difficult to expect good applications with non-polar type of polymer such as in MMM (Mixed Metric Membrane) fabrication. Additionally, the surface modifications are usually attempted by coating with linear surfactants. In this case, porous particle structures are filled by them and this causes decreasing surface area and uneven blocking of the pores. To solve this problem, ring type surfactant is considered which has similar diameter with the pore size of the target materials. As a good candidate, 4-tertbutyl calix[6]arene monomer was chosen. This monomer not only has an amphiphilic property, but also showed a similar pore structure with UIO-66. Calix[6]arene coated UIO-66 particles demonstrated hydrophobic property in toluene with good dispersity, and mixed with polystyrene solution (non-polar type polymer) for polymer film fabrication.In the third chapter, a new preparation of mesoporous carbon structures is introduced by using microwaves and metal oxide nanoparticles. In general, mesoporous carbon structures are synthesized by using inorganic templates such as SiO2 and TiO2 to form the uniform pores. In this methods, carbon sources are filled in the inorganic templates and the templates are removed through post-treatments such as chemical dissolution. However, conventional synthetic methods have weaknesses like requiring long reaction time to get the mesoporous structure. In this research, we obtained highly ordered mesoporous carbon structure from COP (Covalent Organic Polymer) precursor and iron oxide (Fe3O4) nanoparticles mixture by heating under microwave irradiation. Because microwave heating increases the temperature of the solution evenly and efficiently to form the Fe3O4 particles embedded in the polymer structures.In the fourth chapter, a new approach to synthesize mixed metal nanoparticles from natural sea salt is introduced. Basically, synthesize the ordered mixed metal structure is very difficult in nanoscale. In this research, mixed rare metal precursors are extracted from the natural sea salt, and injected in an organic solvent and heated with surfactant to form uniform particles. After then, checked the particle properties using TEM and DLS.Consequently, this thesis focused on the synergy effects and results of organic-inorganic nanocomposites. However, I expect that our science could be more developed by challenging conventional ideas and trying to find new approaches to various fields.