Document Detail

Raman study of the polybenzimidazole-phosphoric acid interactions in membranes for fuel cells.
MedLine Citation:
PMID:  22699788     Owner:  NLM     Status:  Publisher    
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(-1) 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.
Fosca Conti; Anne Majerus; Vito Di Noto; Carsten Korte; Werner Lehnert; Detlef Stolten
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-6-14
Journal Detail:
Title:  Physical chemistry chemical physics : PCCP     Volume:  -     ISSN:  1463-9084     ISO Abbreviation:  -     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-6-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100888160     Medline TA:  Phys Chem Chem Phys     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Institute of Energy and Climate Research - Fuel Cells (IEK-3), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
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