Synthesis And Application Of Hypercrosslinked Porous Polymers Based On Arylimidazole

Hyper-crosslinked polymers?HCPs?are a class of ideal CO₂ adsorbents with low density,stable structure,large specific surface area and reusability.Heteroatoms such as N and O atoms can form hydrogen bonds or dipole-quadrupole interactions with CO₂ molecule.Therefore,the introduction of such atoms into HCPs can increase the CO2 adsorption capacity of the HCPs and the ability to selectively adsorb CO2.In this thesis,2,4,5-tris?4-formylphenyl?-1-butyl-imidazole?TPI?and 1,4-bis?4,5-bis?4-formylphenyl?-1-butyl-1H-imidazol-2-yl?benzene?TPBI?were synthesized from terephthal-aldehyde.Nitrogen-rich HCPs and oxygen-rich HCPs were prepared by reacting the two monomers with melamine and phloroglucin,respectively.The as-synthesied HCPs were characterized by infrared spectroscopy,solid-state NMR and nitrogen adsorption-desorption isotherms.The CO₂ adsorption performance of such HCPs was also investigated.The main research results were as follows:?1?Synthesis and properties of melamine-?tris/tetraphenylimidazole?aldehyde-based organic microporous polymers?SNWs?.The melamine-triphenyl-imidazole aldehyde-based?TPI-SNW?and melamine-tetraphenylimidazole aldehyde-based?TPBI-SNW?hypercrosslinked microporous polymers were synthesized by reacting melamine with TPI and TPBI,respectively.The specific surface areas of TPI-SNW and TPBI-SNW were 718 and 657 m² g^-1,respectively.The pore size distribution of the two polymers was similar,but the pore volume of TPI-SNW was larger,about0.21 cm³ g^-1.The CO₂ adsorption capacity of TPI-SNW is 3.76 mmol g^-1 at 273 K 1bar,and the adsorption capacity is reduced to 2.09 mmol g^-1 when the temperature is raised to 298 K.The CO₂ adsorption performance of TPI-SNW is better than that of TPBI-SNW.According to the Clausius-Clapeyron equation,the CO₂ equivalent adsorption heat of TPI-SNW and TPBI-SNW is 37.5 and 30.8 kJ mol^-1,respectively,and such polymers also exhibit good CO2/N2 selectivity,i.e.,36.9 and 32.3 for TPI-SNW and TPBI-SNW,respectively.TPI-SNW not only has a higher CO₂adsorption capacity,but also has better CO₂ selective adsorption performance due to its larger specific surface area and higher nitrogen content.?2?Synthesis and properties of hypercrosslinked microporous polymers based on phloroglucin-?tris/tetraphenylimidazolium?aldehyde?POFs?.Monomer TPI and TPBI react with phlorogsol via phenolic resin to form hypercrosslinked microporous polymers based on phloroglucinol-triphenylimidazole aldehyde?TPI-POF?and phloroglucinol-tetraphenylimidazole aldehyde?TPBI-POF?.The specific surface area of the polymer is related to monomer concentrations in the polymerization system.When the TPI concentration is 0.2 mol L^-1,the specific surface area of TPI-POF is the largest,reaching 467 m² g^-1.Due to the poor solubility of the TPBI monomer,the TPBI concentration can only reach 0.1 mol L^-1,so the specific surface area of TPBI-POF is only 253 m² g^-1.The pore size distribution of TPI-POF is below 3 nm,mainly dominated by micropores with a micropore pore volume of 0.20 cm³ g^-1.The pore size distribution of TPBI-POF is wide,mainly mesopores and macropores.The micropore volume is only 0.05 cm³ g^-1.The obtained polymers were tested for CO₂adsorption.The adsorption capacity of TPI-POF reached 2.96 mmol g^-1 at 273 K 1bar,and the adsorption performance was better than TPBI-POF.According to the Clausius-Clapeyron equation,the CO2 adsorption heats of TPI-POF and TPBI-POF are 27.7 and 24.8 kJ mol^-1,respectively.The gas selectivity for CO₂/N₂ was then calculated to be 30.7 and 28.8,respectively,for TPI-POF and TPBI-POF according to Henry's law.Also,since TPI-POF not only has larger specific surface area,but also has higher oxygen content,TPI-POF has higher CO2 adsorption amount and better CO2 selective adsorption performance than those of TPBI-POF.