Ionic liquid (IL)/polyimide (PI) composite membranes demonstrate promise for use in CO2 separation applications.However,few studies have focused on the microscopic mechanism of CO2 in these composite systems,which is important information for designing new membranes.In this work,a series of systems of CO2 in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfo-nyl)imide composited with 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)-based PI,6FDA-2,3,5,6-tetramethyl-1,4-phenylene-diamine,at different IL con-centrations were investigated by all-atom molecular dynamics simulation.The formation of IL regions in PI was found,and the IL regions gradually became continuous channels with increasing IL concentrations.The analysis of the radial distribution functions and hydrogen bond numbers demonstrated that PI had a stronger interaction with cations than anions.However,the hydrogen bonds among PI chains were destroyed by the addition of IL,which was favorable for transporting CO2.Furthermore,the self-diffusion coefficient and free energy barrier suggested that the diffusion coefficient of CO2 decreased with increasing IL concentrations up to 35 wt-％ due to the decrease of the fractional free volume of the composite membrane.However,the CO2 self-diffusion coefficients increased when the IL contents were higher than 35 wt-％,which was attributed to the formation of continuous IL domain that benefitted the transportation of CO2.

Linlin You;Yandong Guo;Yanjing He;Feng Huo;Shaojuan Zeng;Chunshan Li;Xiangping Zhang;Xiaochun Zhang

Beijing Key Laboratory of Ionic Liquids Clean Process,CAS Key Laboratory of Green Process and Engineering,State Key Laboratory of Multiphase Complex Systems,Institute of Process Engineering,Chinese Academy of Sciences,Beijing 100190,China;College of Mathematics and Physics,Bohai University,Jinzhou 121013,China;School of Chemical Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Zhengzhou Institute of Emerging Industrial Technology,Zhengzhou 450001,China

化学科学与工程前沿

[1]Linlin You;Yandong Guo;Yanjing He;Feng Huo;Shaojuan Zeng;Chunshan Li;Xiangping Zhang;Xiaochun Zhang-.Molecular level understanding of CO2 capture in ionic liquid/polyimide composite membrane)[J].化学科学与工程前沿,2022(02):141-151

trifluoromethylsulfo,hexafluoroisopropylidene,diphthalic

Molecular,level,understanding,capture,ionic,liquid,polyimide,Ionic,membranes,promise,separation,applications,However,few,studies,have,focused,microscopic,mechanism,these,systems,which,important,information,designing,new,In,this,work,series,butyl,methylimidazolium,bis,composited,anhydride,6FDA,tetramethyl,phenylene,diamine,different,were,investigated,by,atom,molecular,dynamics,simulation,regions,was,found,gradually,became,continuous,channels,increasing,concentrations,analysis,radial,distribution,functions,hydrogen,numbers,demonstrated,that,had,stronger,interaction,than,anions,bonds,among,chains,destroyed,addition,favorable,transporting,Furthermore,self,diffusion,free,energy,barrier,suggested,decreased,up,wt,due,fractional,volume,coefficients,increased,when,contents,higher,attributed,domain,benefitted,transportation

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