Synthesis And Properties Of Organosilicon Porous Materials

Organosilicon materials have been widely applied in many fields, such as aerospace, electron, light industry, mechanics, construction and medicine, owing to the specific structure and properties of silicon atom. Organosilicon materials were developed rapidly in recent years. However, compared to the wide variety of organocarbon materials, there are fewer kinds of organosilicon materials. The development of new functional organic silicon material is still the focus of researchers. Porous organic polymers?POPs? have attracted much attention recently due to their excellent microporous characters, light weight, synthetic diversification, thermal and chemical stability of the organic framework. Compared with the organic carbon-based porous material, silicon-based porous material have many advantages such as monomer ease of synthesis, high specific surface area advantage. However, investigations on organosilicon porous materials start in only recent years.In this thesis, the main task is to design and synthesize several porous organic polymers which derived from tetrahedral silicon-centered monomers. Then these materials were characterized by nitrogen adsorption/desorption isotherms, IR, elemental analysis and solid-state NMR techniques. Applications of these organic polymers in carbon dioxide sorption were also explored. The details are shown as followed:?1? Synthesis and properties of porous organic polymers derived from tetrahedral silicon-centered monomers and stereocontorted spirobifluorene- based precursor. Novel porous organic polymers?POPs?, POP-1 and POP-2, were constructed via Sonogashira-Hagihara coupling reactions from silicon-centered monomers with 2,2',7,7'-tetraethynyl-9,9'-spirobifluorene, tetrakis?4-bromophenyl?silane?p-Si? and tetrakis?3-bromophenyl?silane?m-Si?. In comparison to other porous materials, these materials exhibited relatively high surface area and thermal stability, with SBET of up to 983 m2g^-1,and total pore volumes of up to 0.85 cm3g^-1. Their porosity is tunable by altering the connectable sites of silicon-centered monomers. Gas storage applications revealed that the resulting materials possessed moderate CO₂ uptake of 1.92 mmolg^-1?8.45 wt %? at 273 K, 1.03 bar, and 1.12 mmolg^-1?4.93 wt %? at 298 K, 1.01 bar. Moreover, the materials exhibited moderate selectivity of CO₂ over other gases, including N2, O₂ and CH4. These results reveal that these materials could be potentially applied as promising candidates for storing and capturing CO₂.?2? Synthesis and properties of porous organic polymers derived from tetrahedral silicon-centered monomers and alkynyl pyridine-based precursor. Novel porous organic polymers, POP-3^POP-6, were prepared through Sonogashira-Hagihara coupling reactions from silicon-centered compounds with tetra- bromophenyl groups?p-Si, m-Si? and alkynyl pyridine. Their porosity varied from almost no porosity to high porosity by altering the connectable sites of silicon-centered monomers, and the type of alkynyl pyridine monomers. The best of the resulting materials exhibited comparable specific surface areas with SBET of 410 m2g^-1,with total pore volumes of 0.34 cm3g^-1. And changing the connection position of the silicon unit, POP-3 has a high ratio of micropores, while the POP-4 can be considered to be mesoporous. Although the specific surface area of the materials are not too high, they showed a relatively high CO₂ absorption performance, thereby indicating their potential applications as adsorbents for CO₂ capture or storage.?3? Synthesis and post-synthetic functionalization of fluorenone-based organosilicon porous polymers. The fluorenone unit was ncorporated into the organosilicon porous polymers network to prepare a new polymer of POP-7, and post-synthetic functionalization of POP-7 resulted in POP-8. Although post-synthetic functionalization lead the materials of porous performance and CO₂ adsorption properties were decreased, compared with the properties of the porous, CO₂ adsorption performance was significantly improved to some extent, apparently due to the introduction of the amino group to improve the affinity between the material and CO₂. We provided a new strategy for post-synthetic functionalization of porous materials.?4? Synthesis and post-synthetic functionalization of organosilicon porous polymers. The p-alkyne benzene unit was incorporated into the organosilicon porous polymers network to prepare a new polymer of POP-9, then using the excess alkyne groups for post-synthetic functionalization of POP-9, POP-10 and POP-11 were afforded. Herein, we provided a new method for post-synthetic functionalization of porous polymers usingsulfur, and aliphatic amines. The resulting materials have many potential applications such as heavy metal ions, catalysts and so on.