Polyphenylenebenzimidazoles

Iwakura, Yoshio; Uno, Keikichi; Imai, Yoshio

doi:10.1002/pol.1964.100020611

Cited by 127 publications

(94 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…PBI can also be synthesized in homogeneous solutions with solvents such as polyphosphoric acid (PPA) [80] (see Scheme 4). Taking advantages of a moderate temperature • C) and using more stable monomers (TAB stabilized by tetra hydrochloride), this method is an excellent route for preparing laboratory or small scale batches of linear, high molecular weight polymers, though a relatively large amount of acid solvent and multiple-step isolation procedures are involved.…”

Section: Homogeneous Solution Synthesismentioning

confidence: 99%

“…Poly[2,2 -p-(phenylene)-5,5 -bibenzimidazole] (pPBI, Scheme 5a) was first synthesized in the early 1960s [76,80] and seems of more interest in recent years [86][87][88][89]. Compared with the meta-PBI, the para structure of the polymer showed superior tensile strength and stiffness [90], however, the glass transition temperature was lowered by 59 • C [57], indicating the enhanced flexibility of the polymer chain due to introduction of the p-phenylene linkage in the backbone.…”

Section: Para Pbimentioning

confidence: 99%

See 1 more Smart Citation

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Jensen

Savinell

et al. 2009

Progress in Polymer Science

1,243

852

View full text Add to dashboard Cite

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, acid-base polymer membranes represent an effective approach. The phosphoric acid-doped polybenzimidazole membrane seems so far the most successful system in the field. It has in recent years motivated extensive research activities with great progress. This treatise is devoted to updating the development, covering polymer synthesis, membrane casting, physicochemical characterizations and fuel cell technologies. To optimize the membrane properties, high molecular weight polymers with synthetically modified or N-substituted structures have been synthesized. Techniques for membrane casting from organic solutions and directly from acid solutions have been developed. Ionic and covalent cross-linking as well as inorganic-organic composites has been explored. Membrane characterizations have been made including spectroscopy, water uptake and acid doping, thermal and oxidative stability, conductivity, electro-osmotic water drag, methanol crossover, solubility and permeability of gases, and oxygen reduction kinetics. Related fuel cell technologies such as electrode and MEA fabrication have been developed and high temperature PEMFC has been successfully demonstrated at temperatures of up to 200• C under ambient pressure. No gas humidification is mandatory, which enables the elimination of the complicated humidification system, compared with Nafion cells. Other operating features of the PBI cell include easy control of air flow rate, cell temperature and cooling. The PBI cell operating at above 150• C can tolerate up to 1% CO and 10 ppm SO 2 in the fuel stream, allowing for simplification of the fuel processing system and possible integration of the fuel cell stack with fuel processing units. Long-term durability with a degradation rate of 5 V h −1 has been achieved under continuous operation with hydrogen and air at 150-160• C. With load or thermal cycling, a performance loss of 300 V per cycle or 40 V h −1 per operating hour was observed. Further improvement should be done by, e.g. optimizing the thermal and chemical stability of the polymer, acid-base interaction and acid management, activity and stability of catalyst and more importantly the catalyst support, as well as the integral interface between electrode and membrane.

show abstract

Section: Homogeneous Solution Synthesismentioning

confidence: 99%

Section: Para Pbimentioning

confidence: 99%

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Jensen

Savinell

et al. 2009

Progress in Polymer Science

1,243

852

View full text Add to dashboard Cite

show abstract

“…PBI based acid-base membranes have been proposed by several groups using heteroand homogeneous synthesis. 9,[11][12][13][14][15][16][17][18][19][20] The membranes show high conductivity at low humidity, 21 good thermal and mechanical strength, 22 high CO tolerance 23 and low gas crossover. 24 Among the many possible PBI derivatives, a very promising material is poly(2,5-benzimidazole) (AB-PBI).…”

Section: Introductionmentioning

confidence: 99%

Raman study of the polybenzimidazole–phosphoric acid interactions in membranes for fuel cells

Conti

Majerus

Noto

et al. 2012

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Poly(2,5-benzimidazole) (AB-PBI) membranes are investigated by studying the FT-Raman signals due to the benzimidazole ring vibration together with the C-C and C-H out-of-and in-plane ring deformations. By immersion in aqueous ortho-phosphoric acid for different time periods, membranes with various doping degrees, i.e. different molar fractions of acid, are prepared. The chemical-physical interactions between polymer and acid are studied through band shifting and intensity change of diagnostic peaks in the 500-2000 cm À1 spectral range. The formation of hydrogen bonding networks surrounding the polymer seems to be the main reason for the observed interactions. Only if the AB-PBI polymer is highly doped, the Raman spectra show an additional signal, which can be attributed to the presence of free phosphoric acid molecules in the polymer network. For low and intermediate doping degrees no evidence for free phosphoric acid molecules can be seen in the spectra. The extent of the polymer-phosphoric acid interactions in the doped membrane material is reinvestigated after a period of one month and the stability discussed. Our results provide insight into the role of phosphoric acid as a medium in the conductivity mechanism in polybenzimidazole.

show abstract

“…Melt polycondensation 2,11 and solution polycondensation [12][13][14][15][16] have been frequently used to synthesize PBI and PBO. Attempts have been made to combine polybenzimidazole with polybenzoxazole, in order to obtain more thermal stable and tractable polymers.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Poly (Bibenzimidazole-P-Phenyl- Benzobisoxazole)

Chen

Cui

et al. 2009

J. Chil. Chem. Soc.

View full text Add to dashboard Cite

A diacid monomer of benzobisoxazole 2, 6-di(p-phenylene-carboxylic) acid (BBODPA) was synthesized in a simple procedure, and characterized by means of FTIR, 1 H NMR and 13 C NMR. The resulting BBODPA was polymerized with 3, 3'-diaminobenzidine tetrahydrochloride (DAB) to prepare poly (bibenzimidazolep-phenyl-benzobisoxazole) (PBBIBBO) in polyphosphoric acid. The inherent viscosities values of PBBIBBO indicated that it was a kind of high molecular weight polymer. The structure of PBBIBBO was confirmed by 1 H NMR, 13 C NMR and FTIR. Thermal properties and dissolubility of PBBIBBO were also investigated. These results showed that PBBIBBO exhibited good thermal stability.

show abstract

Polyphenylenebenzimidazoles

Cited by 127 publications

References 3 publications

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

Raman study of the polybenzimidazole–phosphoric acid interactions in membranes for fuel cells

Synthesis of Poly (Bibenzimidazole-P-Phenyl- Benzobisoxazole)

Contact Info

Product

Resources

About