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## Abstract Molecular aggregation of poly(4,4′‐diphenyl ether‐5,5′‐bibenzimidazole)(PBI) in solution has been studied by high resolution proton NMR. PBI and model compounds have been synthesized, purified, and characterized. Proton resonances in the NMR spectrum of PBI are assigned by comparison with the proton resonances of the model compounds. Spectra are studied by total line‐shape analysis, assuming each absorption curve to be Lorentzian. For PBI in __N__,__N__‐dimethylacetamide (DMAc), the resonance due to the proton of a hydroxyl group formed by proton exchange between the imino group of PBI and the carbonyl group of DMAc is observed. The activation energy for the proton exchange, obtained from Arrhenius plots of the temperature dependence of the chemical shifts of the hydroxyl proton and the imino proton, was found to increase in the order corresponding to dissociation energy of the NH···OC hydrogen bond. The chemical shifts in the NMR spectra of PBI‐DMAc solutions on the addition of LiCl are strongly dependent on the polymer‐salt ratio; and thereby the coordination position of LiCl to PBI is tentatively identified, assuming a pseudocontact LiCl‐induced shift. The dependen

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Author

Takakazu Kojima

Publisher

Wiley (John Wiley & Sons); Interscience Publishers; Wiley (ISSN 0098-1273)

Published

1980

Language

EN

Field

Materials Science (Physical Sciences)