Synthesis and Characterization of Sulfonated Poly(Phenylene) Containing a Non-Planar Structure and Dibenzoyl Groups

Abstract

Polymers for application as sulfonated polyphenylene membranes were prepared by nickel-catalyzed carbon-carbon coupling reaction of bis(4-chlorophenyl)-1,2-diphenylethylene (BCD) and 1,4-dichloro-2,5-dibenzoylbenzene (DCBP). Conjugated cis/trans isomer (BCD) had a non-planar conformation containing four peripheral aromatic rings that facilitate the formation of π-π interactions. 1,4-Dichloro-2,5-dibenzoylbenzene was synthesized from the oxidation reaction of 2,5-dichloro-p-xylene, followed by Friedel-Crafts reaction with benzene. DCBP monomer had good reactivity in polymerization affecting the activity of benzophenone as an electron-withdrawing group. The polyphenylene was sulfonated using concentrated sulfuric acid. These polymers without any ether linkages on the polymer backbone were protected from nucleophilic attack by hydrogen peroxide, hydroxide anion, and radicals generated by polymer electrolyte membrane fuel cell (PEMFC) operation systems. The mole fraction of the sulfonic acid groups was controlled by varying the mole ratio of bis(4-chlorophenyl)-1,2-diphenylethylene in the copolymer. In comparison with Nafion 211 ® membrane, these SBCDCBP membranes showed ion exchange capacity (IEC) ranging from 1.04 to 2.07 meq./g, water uptake from 36.5% to 69.4%, proton conductivity from 58.7 to 101.9 mS/cm, and high thermal stability.

Preparation of tungstic acid functionalized titanium oxide nanotubes and its effect on proton exchange membrane fuel cell

“…So, researchers have been working on developing cost efficient and ecofriendly polymer membranes consisting of hydrocarbon backbone. High engineering polymers such as poly ether ether ketone (PEEK) [5], Poly styrene-ethylene-butylenestyrene (PSEBS) [6], poly(ether sulfone) (PES) [7], polyimide (PI) [8], poly vinyl imidazole (PVIM) [9], polyphenylene (PPE) [10] and polybenzimidazole (PBI) [11], etc. have been subjected to modification (sulfonation) to replace Nafion [12].…”

Synthesis of novel sulfonated poly(arylene ether)s containing a tetra-trifluoromethyl side chain and multi-phenyl for proton exchange membrane fuel cell application

“…Moreover, the worst disadvantage is high material costs due to expensive uorination and complex manufacturing processes. [5][6][7][8] In recent years, sulfonated hydrocarbon polymers have attracted signicant attention as alternative polymer electrolyte membranes to Naon. These sulfonated polymers, such as sulfonated poly (arylene ethers), sulfonated poly(arylene ether ketone)s, sulfonated polyimides, and sulfonated polybenzimidazoles, 9,10 have been extensively investigated owing to the easy adjustment of their molecule structure, high thermal stability, good chemical stabilities, appropriate mechanical properties, processability, and low production cost.…”

On the evolution of sulfonated polyphenylenes as proton exchange membranes for fuel cells

“…Since 2014 W. Kim and co-workers, 53,54,[56][57][58][59][60][61][62][63]55 reported on a number of side-chain sulfonated polyphenylene variants for PEMFC applications. These polyphenylenes, which were all prepared through Ni-catalyzed cross-coupling reactions of dichlorophenyl monomers, contained various combinations of tetraphenylethylene and/or benzoyl moieties, including branched and alkyl-chain-grafted derivatives.…”

“…al. 53,54,[56][57][58][59][60][61][62][63] based on sulfonated poly(benzophenone)s, yield materials with IEC values ranging from 1 to 3 meq. g -1 and varying water sorption and electrochemical characteristics for a given IEC, which demonstrates structure-property tunability in sulfonated polyphenylenes.…”

“…1 These requirements are highlighted in Figure 1. Despite comprehensive investigation and ubiquitous application, 58 the fundamental structure of PFSAs has remained largely unchanged for over 50 years (Figure 2), 9,10,11,12 and is inherently challenging. There is a growing concern surrounding environmental implications of perfluorinated chemical use.…”