Alkaline anion exchange membrane fuel cells (AEMFCs) have been explored as attractive alternatives to PEFCs because oxygen reductive reaction kinetics can be increased, and the use of non-precious metal electrocatalysts can be achieved. In order to develop AEMFCs, a new hydrophilic monomer, 2,5-dichlorophenyl(4-(3-(trimethylphosphonio)propyl)benzoyl)-1,4-phenylene (P-PrDBP), was designed. The alkaline stability of phosphonium group is superior to that of ammonium analogues. In this study, we synthesized random copolymers consisting of hydrophilic poly(4-(3-(trimethylphosphonio)propyl)benzoyl)-1,4-phenylene (P-PrPBP) and hydrophobic poly(4-phenoxy benzophenone) (PPBP), and the effect of unit ratio on hydroxide conductivities was investigated. P-PrDBP and 2,5-dichloro-4’-phenoxy benzophenone (DPBP) were polymerized via nickel-catalyzed coupling polymerization to obtain the copolymers (PPr-r-PPBP (x:y)) with varying the composition ratio. The x:y indicates the composition ratio of P-PrPBP and PPBP. In FT-IR measurements, the stretching vibration of C-Cl bond disappeared for PPr-r-PPBP (x:y), suggesting that the polymerization proceeded. The contents of phosphonium group in PPr-r-PPBP (x:y) copolymers were calculated by 1H NMR to be almost the same with the theoretical values. The content of phosphonium group in the copolymers was controllable by the feed ratio of P-PrDBP and DPBP. The ion exchange capacity values of PPr-r-PPBP (1:2), (1:1), and (2:1) were 1.23, 1.68, and 2.29 meq g-1, respectively. The polymer membranes were obtained by using cast method with dimethylsulfoxide solutions and were dried at 80 °C for 24 h. The obtained membranes were immersed in 1 M NaOH solution at room temperature for 24 h to exchange bromide ions for hydroxide ions and were washed with deionized water. The hydroxide conductivity values of PPr-r-PPBP (1:2), (1:1), and (2:1) membranes were 1.5, 7.0, and 12 mS cm-1, respectively, at 80 °C and 100%RH.

Synthesis and evaluation of polyphenylene-based electrolytes having phosphonium group (IV): Effect of unit ratio on hydroxide conductivities

256th National Meeting (2018)

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