Synthesis And Properties Of Multi-Sulfonated Poly (arylene Ether)s For Proton Exchange Membranes

Proton exchange membrane fuel cells (PEMFCs) have attracted particular interest due to their wide range of potential applications in areas such as portable and stationary power generation, personal electronic devices (e.g., mobile phones, laptop computers),and automobiles. As the key component in PEMFCs,the proton exchange membrane (PEM) must possess several characteristics including high proton conductivity, low electrical conductivity, low permeability to fuel and oxidant, oxidative and hydrolytic stability, balanced water transport, good mechanical properties, and the capability to be assembled into a membrane electrode assembly (MEA) at low cost. The ability of a PEM to mediate the transport of protons, typically via acid-bearing functionalities (e.g., sulfonic acid groups),is essential in order to achieve high levels of power generation.Under moderate operating conditions (temperature (T)<90℃, relative humidity (RH)≈100%), state-of-the-art membrane based on perfluorosulfonic acid (PFSA) ionomer(e.g., Nafion,117) as opposed to hydrocarbon ionomers (e.g.,sulfonated poly(ether ether ketone), SPEEK), and exhibit high levels of proton conductivity, water transport, and durability. However, under the more stringent operating conditions requested by industry (T>100℃, RH<50%), proton conductivity for PFSA membranes drops significantly, leading to a decrease in fuel cell performance. Thus, there is considerable interest in the development of new membranes with greatly improved levels of proton conduction for high T and low RH operation, but this requires a greater understanding of the factors that affect proton transport in these materials.In this thesis, we attempt to used multi-sulfonated segment to improve the morphology for improved performance of sulfonated poly(arylene ether)s. The first, we design and synthesis of four sulfonated difluoro-monomer(TSFDK).the monomer structure was confirm by NMR and FT-IR instrument. The results prove that we got objective component. Then corresponding poly(arylene ether)(SPAE) was also prepared by copolymerization form above monomer and commercial monomers. The obtained sulfonated polymers have a high viscosity properties reveal in the polymers have molecular weight. The transparent and tough membrane was obtained by solution casting method, and thick about 100μm.We also study on polymer properties in detail. Water uptake of sulfonated polymer is very closely related to conductivity and mechanical strength of polymer. Those sulfonated polymer exhibited moderate water uptake is below 30%and low swelling ratio at high temperature and high sulfoned degree. High sulfonated polymer exhibited high proton conductivity above 10-2 S/cm at room temperature, and low methanol permeability and excellent mechanical properties.