Preparation And Properties Of High Performance Imidazole Crosslinked Anion Exchange Membrane

For the past few years,anion exchange membrane fuel cell(AEMFC),as a kind of fuel cell,has become a hots research topic because of its advantages of faster reaction kinetics and low preparation cost.The anion exchange membrane(AEM)not only acts as a transport OH~-but also separates the cathode and anode in AEMFC,so the performance of AEM directly determines the performance of the AEMFC.At present,AEM common problem is that conductivity and alkali resistance stability can not be improved at the same time.In order to overcome this problem,we chose poly(aryl ether ketone)(PAEKS)as the main chain with both rigid benzene ring structure and flexible ether bond,and introduced different performance side chain cationic groups to prepare AEM.In the second chapter,binary PAEKS was prepared with methyl hydroquinone and 4,4-difluorodiphenyl ketone as monomers.A series of CIm TPAEKS membranes prepared by grafting trimethylamine with high conductivity and 1-vinylimidazole with good alkali-resistant stability base on poly(aryl ether ketone).The experimental results show that the CIm TPAEKS membrane has high ionic conductivity.Among them,the conductivity of CIm TPAEKS-1 membrane is the highest,reaching 0.083 S/cm at 80 ℃.The 1-vinylimidazole is cross-linked in AEM,which improves the dimensional stability of the membrane.When the sample membranes are immersed in 2 M Na OH solution at 80 ℃ for 15 days,the ion conductivity of CIm TPAEKS-1 membrane is 0.051 S/cm.In order to further improve the alkali resistance stability of AEM.In the third chapter,on the basis of the monomer in the second chapter,we introduced a monomer containing double bonds to prepare a kind of ternary PAEKS containing double bonds.Grafting1-allyl-3-methyl imidazole chloride and 1-vinylimidazole with good alkali resistance stability as side chains to prepared a series of CSIm PAEKS membranes base on PAEKS.The imidazole in the membrane can act as the donor and acceptor of the ion,and OH~-constantly jumps forward between the two kinds of imidazole groups.At the same time,two kinds of imidazole groups with different chain length help to form a large number of OH~-transport paths in the membrane,which promotes the transport of OH~-.The experimental results show that CSIm PAEKS membrane has high OH~-conductivity,and the OH~- conductivity of CSIm PAEKS-3 membrane is the highest at 80 ℃,reaching 0.1357S/cm.After soaking the membrane in 2 M Na OH solution at 80 ℃ for 400 h,the OH~-conductivity of the membrane decreased to 0.0936 S/cm,showing excellent conductivity and alkali resistance stability.The crosslinking structure was formed between1-vinylimidazole,which effectively improved the mechanical properties of the series membranes.The tensile strength of CSIm PAEKS-3 membrane can reach about 30 MPa,which is expected to be used in AEMFC.In order to further enhance the combination property of AEM.In the fourth chapter,we chose to prepare novel polymethyl-site PAEKS by polycondensation of trimethylhydroquinone instead of methylhydroquinone on the basis of the third chapter.A series of TCSIm P membranes was prepared by introducing the same two kinds of imidazole groups.A large amount of 1-vinylimidazole was grafted into the membrane,which not only improved the OH~-conductivity and chemical stability of the membrane,but also played the role of crosslinking agent in the membrane,which effectively improved the mechanical properties of the membrane.The experimental results show that the OH~-conductivity of TCSIm P-3 membrane was 0.144 S/cm at 80 ℃,and it can still reach 0.117S/cm after alkali treatment.The tensile strength of the membrane is above 70 MPa,which meets the application conditions of fuel cell.