Study On Synthesis And Adsorption Performance Of Aromatic Spirocyclic Organic Microporous Polymers

Nowadays the environmental problems is more and more serious because of the consumption of fossil fuel in quantity, which threat of human sustainable development. Therefore, utilizing new and clean energy source, such as hydrogen, and capture carbon dioxide and toxic organic molecules are very important to meet the energy and environmental demands. Nearly half a century, lots of efforts worldwide have been devoted to explore suitable materials for efficient and safe storage of hydrogen or capture of carbon dioxide. Porous organic polymers with large specific surface area, narrow pore size distribution, low skeleton density, controlled surface functionality, and high chemical and physical stability, have exhibited potential applications in energy, environment, catalysis and biomedical areas, especially in hydrogen storage and carbon dioxide capture and separation, which has tremendous significance in solving the problems of energy and environment. According to the design strategies and the structural character, the porous organic polymers have been classified to four type, hypercross-linked polymers, conjugated microporous polymers, polymers of intrinsic microporosity, and covalent-organic frameworks. Different type of porous organic polymers have different characters, such as in solubility, morphology, specific surface area, pore size distribution, and have different application performance, such as in gas storage, carbon dioxide capture and separation, catalysis. In this paper, using aromatic spirocyclic compounds as core building units, a series of porous organic polymers were synthesized and characterized, and the applications of them were also investigated.Using aromatic spirocyclic compound2,2’,7,7’-tetrabromospiro-bixanthene (TBSBX) as core building unit, with4,4’-biphenyldiboronic acid, new microporous polymeric sphere PSBX with particle size of about600nm have been successfully prepared through the surfactant-free Suzuki coupling polymerization in a single-phase. The Brunauer-Emmett-Teller specific surface area for the polymer is up to1020m2g-1and the dominant pore size is centered at0.59nm. Its hydrogen storage can reach to1.67wt%at1.0bar and77K and the uptake capacity for carbon dioxide is12.0wt%at1.0bar and273K. The mass ratio of adsorbed H2O to methanol is about1:15at saturated vapor pressure and room temperature, which could be more useful to extract methanol from water in practical applications. Its toluene adsorption is up to887mg g"1at saturated vapor pressure and room temperature, which show potential use in gas uptake and elimination of harmful small molecules in the environment.Using aromatic spirocyclic compound2,2’,7,7’-tetrabromospiro (fluorene-9,9’-xanthene)(TBSFX) as core building unit, with biphenyl-diboronic acid, new microporous polymeric sphere PSFX with particle size of about200-300nm have been successfully prepared through the surfactant-free Suzuki coupling polymerization in a single-phase. The polymer (PSFX) exhibits permanent microporous nature with Brunauer-Emmett-Teller specific surface area up to610m2g-1and the dominant pore size is centered at0.61nm. Its hydrogen storage can reach to1.20wt%at1.0bar and77K and the uptake capacity for carbon dioxide is11.8wt%and for methane is4.16wt%at1.0bar and273K. At the same time, they all have good CO2/N2and CH4/N2selectivity. PSFX is a highly hydrophobic material with good sorption capacity for toluene (887mg g-1at saturated vapor pressure and room temperature), meanwhile, the sorption capacity of PSFX for water measured at saturation condition and298K is only46mg g-1. PSFX exhibits a remarkable fluorescent emission property in the suspension. Fluorescence detection of explosive chemical (TNT) was performed through a series of spectrofluorometric titration using the suspension of PSFX as the probe.Based on the high reactivity of the C-H bonds in1,2,4,5-tetrafluorobenzene for direct arylation, using aromatic spirocyclic compound2,2’,7,7’-tetrabromo-9,9’-spirobifluorene(TBSBF) as core building unit, with 1,2,4,5-tetrafluorobenzene, new fluorinated porous was smoothly prepared via direct C-H arylation polycondensation, and characterized by solid-state13C NMR and XPS. The obtained polymer shows good thermal and chemical stabilities and high porosities with Brunauer-Emmett-Teller specific surface areas up to700m2g-1. FPSBF exhibits a relatively narrower PSD with the dominant pore size at about0.63nm, and shows good gas uptake capacities for hydrogen (1.30wt%at1.0bar and77K) and methane (4.80wt%at1.0bar and273K). Moreover, its high CH4/N2adsorption selectivity makes the material possess potential application in gas separation.