Synthesis And Characterization Of Sulfonated Polybenzimidazoles By Direct Polycondensation For Proton Exchange Membranes

Proton Exchange Membrane (PEM) is one of the key components for proton exchange membrane fuel cells (PEMFC). Perfluorosulfonic acid polymer membranes widely used at present, such as Nafion, exhibit low conductivity at high temperature, limiting their application at temperatures higher than 100℃. Due to Grotthuss mechanism of proton conduction, Polybenzimidazole (PBI) based PEM could conduct protons without water, showing attraction in potential applications of PEMFC at high temperature.PBI based PEM could be divided into three kinds, including acid-base doped PBI membranes, chemical grafting PBI membranes and direct polycondensation PBI membranes. Though possessing various advantages, they still can't meet the demands of application as PEM. For example, poor solubility is one of their drawbacks. From the molecular design of viewpoint, a series of PBI based PEM with good solubility have been designed and prepared, the properties of which have been preliminarily characterized in this dissertation.At first, sodium-2,2'-disulfonate-4,4'-oxybenzoic acid was successfully synthesized, the structure of which was confirmed by ¹H-NMR, ¹³C-NMR, Dept135 and IR.A series of diphenyl ether based sulfonated polybenzimidazoles were prepared by direct polycondensation of sodium-2,2'-disulfonate-4,4'-oxy -benzoic acid (SDOBA) and 4,4'-oxybenzoic acid (OBA) with...