Proton Magnetic Spectra of Poly(Meta-Phenylene Bibenzimidazole)-Lithium Chloride Solutions in Dimethyl Acetamide
Abstract
The proton magnetic resonance spectra of PBI (poly(meta-phenylene bibenzimidazole)) and model compound, 2,2'-diphenyl-5,5'bibenzimidazole, in N, N'-dimethylacetamide have revealed a large downfield shift of the benz proton singlet in the polymer as compared to the model compound. Lithium chloride has been shown to have a concentration dependent effect on this chemical shift, increasing the shift through a maximum and then decreasing at higher concentrations of lithium chloride. Similar effects have been found for lithium bromide. These chemical shift changes are attributed to conformational changes in the polymer and can provide a measure of the degree of expansion of the macromolecule. This information indicates that the conformation of PBI in solution can be altered by manipulation of lithium chloride concentration, and thus provides a potential route to the preparation of anisotropic films and fibers having enhanced physical properties.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1973
- Accession Number
- AD0769342
Entities
People
- M. T. Ryan
- T. E. Helminiak
Organizations
- Air Force Research Laboratory