Preparation And Property Of Sulfonated Polybenzimidazole Proton Exchange Membrane

Proton exchange membrane?PEM?which was component of fuel cells had a very important role,and its performance index directly determined the service life of fuel cell.At present,the most of the proton exchange membranes were Nafions produced by the United States DuPont Co,althoughgood chemical stability,thermal stability,high conductivity and good mechanical strength made it to be used in the harsh conditions of acid,alkali and oxidant medium and high temperature,but high degree of dependence on water and poor proton conductivity under high temperature,high methanol permeability and high production costs have already limited the use of perfluorinated sulfonic acid proton exchange membrane.The development of new non-fluorinated proton exchange membranes with low cost and low methanol permeability is of great significance to the further application of fuel cells.Polybenzimidazole-based sulfonic acid proton exchange membranes were divided into four types,namely,acid alkali doping type,grafting type,direct sulfonation type,direct polycondensation type.Polybenzimidazole proton exchange membranes that as the proton exchange membranes without fluoride had more excellent proton conductivity over perfluorinated proton exchange membranes,which could realize the rapid spread of proton in anhydrous conditions,conductivity influence low at high temperature.Therefore,the type of polybenzimidazole proton exchange membranes as new generation of proton exchange membranes had more important research values.The traditional polybenzimidazole proton exchange membranes were synthesized with3,3',4,4'-four aminobiphenyl and isophthalic acid and its ester as monomers.We synthesized sulfonated polybenzimidazole proton exchange membranes by using free radical polymerization mechanism.We synthesized 2-?4-vinyl benzene?-1H-benzimidazole precursorp-vinyl benzaldehyde,and its molecular structure was confirmed by ¹HNMR spectra and ¹³CNMR spectra.A sulfonic acid sodium salt was obtained on the basis of p-vinyl benzaldehyde,And then 2-?4-vinyl benzene?-1H-benzimidazole was obtained,sodium sulfonate polymers with benzimidazole groups were obtained by polymerization of p-vinyl benzenesulfonateand2-?4-vinylbenzene?-1H-benzimidazoleas monomers.Sulfonatedpolybenzimidazole proton exchange membrane was preparation by further acidification.Thermodynamic stability,deformation stability,antioxidant capacity and methanol permeability were evaluated by thermogravimetric analysis,differential scanning calorimetry test,water absorption test,swelling test,antioxidant ability test,methanol permeability test of proton exchange membrane,which showed that the sulfonated polybenzimidazole proton exchange membrane prepared had lower water absorption,water absorption rate remained below 15%and the amplitude of variation was small,the amplitude of variation was not more than 4%.At the same time,it had the characteristics of low swelling ratio,the swelling rate was not more than 6%,the swelling rate range was small,and the range of swelling ratio was below 3%;the oxidation resistance study showed that the prepared polymer proton exchange membrane had strong oxidation resistance,and methanol permeability results showed that the methanol permeability of the polymer proton exchange membrane was low.The sulfonatedpolybenzimidazoleproton exchange membrane can be further applied to new fuel cells.