Proton Conducting Membranes Based on Poly(2,2′‐imidazole‐5,5′‐bibenzimidazole)

Abstract

Poly(2,2′‐imidazole‐5,5′‐bibenzimidazole) (PBI‐imi) was synthesized via the polycondensation between 3,3′,4,4′‐tetraaminobiphenyl and 4,5‐imidazole‐dicarboxylic acid. Effects of the reaction conditions on the intrinsic viscosity of the synthesized polymers were studied. The results show that the molecular weight of the polymers increases with increasing monomer concentration and reaction time, and then levels off. With higher reaction temperature, the molecular weight of the polymer is higher. With the additional imidazole group in the backbone, PBI‐imi shows improved phosphoric acid doping ability, as well as a little higher proton conductivity when compared with widely used poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole] (PBI‐ph).Whereas, PBI‐imi and PBI‐ph have the similar chemical oxidation stability. PBI‐imi/3.0 H3PO4 composite membranes exhibit a proton conductivity as high as 10–4 S cm–1 at 150 °C under anhydrous condition. The temperature dependence of proton conductivity of acid doped PBI‐imi can be modeled by an Arrhenius equation.

Recent advances in polybenzimidazole/phosphoric acid membranes for high‐temperature fuel cells

“…However, it is not yet known whether this effect is largely due to the extra protonic groups or due to the morphological changes that occur with the changes in chemical structure. Indeed, a similar effect can be observed in PBI functionalized with pendant benzimidazole 31 or additional main-chain imidazole 32 moieties. In the case of benzimidazole-functionalized PBI, the additional protonic groups show a slightly lowered proton conductivity compared to m-PBI at a given PA content, but the functionalized PBI, being more amorphous and with more protonic groups available, is able to take up a greater amount of PA compared to m-PBI and thus ultimately to show greater proton conductivity.…”

Macromolecular covalently cross-linked quaternary ammonium poly(ether ether ketone) with polybenzimidazole for anhydrous high temperature proton exchange membranes

“…The W doping of PA-PEEK-x%PBI membranes was much higher than 224 wt.% which was higher than that of pure PBI (146 wt.%, immersing in 85 wt.% PA solution at 80 C for 48 h) in our previous work 10. Compared with various levels of PBI-im and PBI-ph in the previously reported work,35…”

A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes

“…Carbon black (Vulcan XC-72R) was purchased from Cabot Chemical Co., Ltd. Poly[2,2’-(2,6-pyridine)-5,5′-bibenzimidazole] (PyPBI) ( Fig. 1a ) was synthesized according to a previously reported method 40 . The MWNT/PyPBI, CB/PyPBI, CB/PyPBI/Pt and MWNT/PyPBI/Pt composites were prepared according to our previous reports 12 14 .…”