Synthesis And Properties Of High Performance Photo-crosslinkable Polysulfone Anion Exchange Membrane

The performance,efficiency and life of FC?Fuel Cell?were determined by the structure and properties of AEM?Anion Exchange Membrane?.Low ionic conductivity and alkaline stability of AEM are the two major problems.In this paper,two kinds of UV-crosslinkable high quaternary polysulfone AEMs were prepared?main-chain type and side-chain type?.The effects of structure and crosslinking degree on the micro-phase structure and properties of the AEMs were discussed,and AEMs with good properties was prepared.In this paper,a polysulfone with chloromethylation rate of 200%?CMPSF200?was synthesized.Then,a series of photosensitive polysulfone?CMPSF200-HCx?was synthesized by reacting with 4-hydroxyl chalcone?4-HC?,and its structure was characterized by ¹H NMR,FT-IR and UV-Vis.The CMPSF200-HCx show good photosensitivity and have the maximum absorption peak at 340 nm.Under UV irradiation,the>C=C<of the chalcone structure on the polymer side chain go through a[2+2]photochemical reaction and form crosslinking structure,and the maximum cross-linking degree can reach 82.3%.A series of photosensitive quaternary polysulfone QCMPSF200-HCx membranes were prepared by quaternalization and alkalization of CMPSF200-HCx.The cQCMPSF200-HCx membranes were obtained under UV irradiation for different time at room temperature.CMPSF200-HCx series and QCMPSF200-HCx films show good solubility in DMF,DMAc,DMSO,THF,NMP and CHCl₃,but cQCMPSF200-HCx are insoluble in any solvent and show good solvent resistance.The QCMPSF200-HCx film had good thermal stability before and after crosslinking,and the initial decomposition temperature was higher than 180 ?.The IEC value of QCMPSF200-HCx films before and after crosslinking was between 1.58².12 mmol g^-1 and IEC value slightly decreased after crosslinking.The water absorption and swelling rate of cQCMPSF200-HC50-6min decreased to 46.69%and 47.76%compared with that of QCMPSF200-HC50 at 30 ?.The ionic conductivity???of QCMPSF200-HCx films were in the range of 12.80²0.74mS/cm at room temperature,and it increases with the increase of temperature and quaternary ammonium salt,it show a value of 135.88 mS/cm at 80 ?,the value of?decreases very little after crosslinking.After soaking the cQCMPSF200-HC70 film and cQCMPSF200-HC60-6min film in 1mol/L NaOH solution at 60 ? for 7 days,the membrane remains intact,and the residue ratios of IEC values were in the range of77.97%⁸7.34%%and the residue ratio of ionic conductivity for cQCMPSF200-HC70-6min was up to 83.36%.The alkaline stability can be improved by crosslinking and increased with the amount of chalcone groups and degree of crosslinking.The photosensitive QCMPSF200-HC70-NC6NC6Br polymer with long alkyl chain and double cation group on the side chain was synthesized by the reaction of CMPSF200-HC70 with the ionic liquid NC6NC6Br.The quaternized film was prepared by solution casting method,and then the cQCMPSF200-HC70-NC6NC6OH membranes were obtained under UV irradiation for different time at room temperature.The QCMPSF200-HC70-NC6NC6OH film show good thermal stability before and after crosslinking,and the initial decomposition temperature was higher than 200 ?.The IEC values of QCMPSF200-HC70-NC6NC6OH were in the range of 1.48¹.64mmol g^-1,which is equivalent to the IEC value of the main chain type QCMPSF200-HC70 series,but its dimensional stability is greatly improved.QCMPSF200-HC70wasdissolvedinthewaterwhile QCMPSF200-HC70-NC6NC6OH maintained intact at 80 ? after two days.After crosslinking,the water absorption rate and swelling rate of anion exchange membrane decreased by 79.63%and 72.53%respectively.The ionic conductivity of QCMPSF200-HC70-NC6NC6OH was in the range of 35.76⁴4.01mS cm^-1 at room temperature and increased with the increase of temperature.The maximum ionic conductivity of QCMPSF200-HC70-NC6NC6OH can reach 148.5 mS/cm at 80?,which was 2.5 times compared with the main chain type QCMPSF200-HC70.Compared with the main-chain QCMPSF200-HC70 films,the side-chain QCMPSF200-HC70-NC6NC6OH films show a better microphase separation structure.After 7 days of immersion in 1mol/L NaOH at 60 ?,the membranes were intact,showing a good alkaline stability,and the residue percentage of ionic conductivity?68.19%?QCMPSF200-HC70-NC6NC6OH,the residue percentage of ionic conductivity for cQCMPSF200-HC70-NC6NC6OH-6min was up to 89.46%compared to that of QCMPSF200-HC70-NC6NC6OH?68.19%?.The alkaline stability was greatly improved by crosslinking.