Study On Preparation And Properties Of Sulfonated Poly(Ether Ether Ketone) Based Composite Proton Exchange Membranes With High Methanol Barrier Properties

As the world’s most widely used on proton exchange membrane, Nafion has some shortcomings, such as unsuited for high temperature working environment, too expensive, environmental pollution and other issues. For this reason, the development of non-fluorinated proton exchange membrane which has low cost, and high performance has become a hot spot of the research on fuel cell. Although the non-fluorinated proton exchange membrane has low cost and methanol permeability, it’s property has a certain gap from Nafion. In order to meet the needs of practical application, it must modify the non-fluorinated proton exchange membrane by physical or chemical methods. In this paper, the sulfonated polyether ether ketone (SPEEK) is the research object, and the key point focuses on the research of modification. The aim is to combine the high proton conductivity of composite membrane and other excellent properties.Despite the proton conductivity of the SPEEK membrane which has high degree of sulfonation is very high, SPEEK is not suitable to the work environment of fuel cells owing to the poor mechanical stability. The swelling can easily happen. Under different sulfonation time in this experiment, preparation of the different degree of sulfonation of SPEEK was performed. In order to enhance the property, the SPEEK was blended with poly(vinylidene fluoride)(PVDF) which had good mechanical properties and dimensional stability to prepare SPEEK/PVDF composite membranes. We explored the change of the parameters of composite membranes such as proton conductivity, methanol permeability, water absorption and dimensional stability through changing the doping amount of PVDF. Analyzed the causes of the change of parameters existed in the study.In this experiment, SPEEK/MMT and SPEEK/OMMT composite membrane was prepared after the SPEEK composited with montmorillonite (MMT) and organic modified montmorillonite (OMMT) which had good dispersion and stability. We analyzed the changes in various parameters of composite proton exchange membrane by changing the clay content. Besides, we used SEM and TEM to contrast the composite effect and the dispersivity of the composite materials, and then chose composite membrane which had better comprehensive performance.The methods to modify SPEEK membrane such as compositing and blending can further improve the dimension stability and mechanical properties of the membrane under the condition of maintaining high proton conductivity. There is an important practical significance for SPEEK to be applied in DMFC.