Synthesis and characterization of sulfonated polyphenylene containing benzophenone moiety via nickel catalyzed polymerization

Graphical abstract: Synthesis and characterization of sulfonated polyphenylene containing benzophenone moiety via nickel catalyzed polymerization. - Highlights: • The active new monomer, 1,6-dichloro-2,5-dibenzoylbenzene, was synthesized. • The sulfonated polyphenylenes containing benzoyl moiety were synthesized with high molecular weight using Ni(II) and Zn catalysts. • Carbon-carbon structures membranes showed good performance with high proton conductivity. - Abstract: The synthesis of polyphenylenes containing benzoyl moiety (PPBP), their functionalization with sulfonic acid groups, and the measurement of properties for PEMs are described. The new monomer was synthesized from an oxidation reaction of 2,5-dichloro-p-xylene, followed by Fridel-craft reaction with benzene. The polymerization was performed by a Ni-catalyzed carbon-carbon coupling reaction of 1,6-dichloro-2,5-dibenzoylbenzene, followed by a sulfonation reaction with chlorosulfuric acid. Compared with Nafion 211^® membrane, these SPPBPs showed rational IECs from 1.47 to 2.51 meq./g, water uptake from 54.1 to 88.4%, proton conductivity from 80.6 to 108.6 mS/cm, and high thermal stability. The proton conductivity was higher than Nafion 211^®. These results showed that the morphology of the polymer matrix was greatly affected by the membranes' properties and stability. Membranes, including benzoyl segments without ether linkage, also provided good dimensional stability in spite of high IEC values. The properties of SPPBPs were very remarkable for fuel cell membrane application. This research demonstrated the possibility of promising SPPBP membranes for excellent proton conductivity