Green And Highly Efficient Preparation Of Microporous Organic Polymers And Investigation Of Their Gas Adsorption Performance

Microporous organic polymers(MOPs)have been developed rapidly in recent years due to their high surface area,light skeleton density,superior environmental stability and great application potential in gas adsorption,wastewater treatment,drug delivery and catalysts.However,environmental friendly,low cost and large-scale preparation of high performance MOPs still remains challenges.In this thesis,three kinds of MOPs,including microporous polybismaleimides,microporous polyimides and microporous polymaleimides,were successfully synthesized and their gas uptake and separation properties were further investigated.The main contents are as follows:(1)Three kinds of microporous polybismaleimides(MPBs)were successfully synthesized from individual bismaleimide(BMI)monomers through sample thermalinitiated radical homopolymerization using diphenyl sulfone(DPS)as solvent in 6 h.FT-IR,13C NMR,EA,TGA and N2 sorption-desorption characterizations confirmed that the obtained MPBs display the expected chemical structure,good environmental stability and high surface area(1025 m2 g-1).Owing to the abundant micropores and heteroatoms,MPBs show excellent CO2 uptake(13.25 wt%,273 K/1.0 bar;8.31 wt%,298 K/1.0 bar)and separation(CO2/N2:64.55,273 K)performance.Additionally,MPBs also display high energy gases(H2:1.05 wt%,77.3 K/1.13 bar;CH4:0.64 mmol g-1,273 K/1.0 bar)and volatile organic compounds(dichloromethane:2800 mg g-1,ethyl acetate:1340 mg g-1,benzene:1380 mg g-1,toluene:1330 mg g-1 and cyclohexane:860 mg g-1)capture capacity.Moreover,DPS can be recovered by rotary evaporation of the extraction solution.During the polymerization,neither an initiator is needed nor are by-products formed.Therefore,the environmental friendly,time-saving and atomeconomic characters endow this strategy with great industrial application prospects.(2)A series of microporous polyimides(MPIs)were synthesized via thermal polycondensation using aromatic trimaines and 1,4,5,8-naphthalenetetracarboxylic dianhydride as building blocks and diphenyl sulfone(DPS)as solvent.The obtained MPIs were characterized by FT-IR,13C NMR,EA,TGA and N2 sorption-desorption measurements.The polycondensation can be completed in 30 min,and the resultant MPIs exhibit good thermal stability and high surface area(1825 m2 g-1).Moreover,MPIs display outstanding NH3 capture performance(21.10 wt%,303 K/1.0 bar)due to the synergistic effect of physical adsorption origined from porous structures and chemical adsorption between NH3 molecules and hrdrogen bond donors(N,O).The recycled MPIs still uptake 19.24 wt%NH3,indicative of the favorable recyclability of MPIs.Besides,MPIs also demonstrate good storage and separation performance towards CO2,H2 and volatile organic compounds.DPS solvent can be recycled for three times and the corresponding product remains high surface area.Therefore,this thermal polycondensation achieve the goals of highly efficient,green and low-cost preparation of microporous polyimides with high performance.(3)Aromatic trimaines(or aromatic diisocyanates)and maleic anhydride were employed as building blocks to undergo one-pot imidization reaction and thermalinitiated radical polymerization at 280? to form microporous polymaleimides(MPMIs).FT-IR,EA and N2 sorption-desorption measurement were carried out to characterize the chemical and pore structures of MPMIs.The products with a high surface area of 730 m2 g-1 can be obtained in 6 h.Moreover,MPMIs have a good application prospect in CO2 uptake and separation.The CO2 adsorption capacity is up to 13.29 wt%(273 K/1.0 bar)and the CO2/N2 selectivity reaches up to 87.83(273 K).During the polymerization,diphenyl sulfone were used as solvent and can be reused at least for three times.Thus,this strategy greatly shortens the reaction time,avoids the complex reaction and purification process,as well as reduces the waste generation.