727694-92-0Relevant articles and documents
A new sequence isomer of AB-polybenzimidazole for high-temperature PEM fuel cells
Gulledge, Alexander L.,Gu, Bin,Benicewicz, Brian C.
, p. 306 - 313 (2012)
A new sequence isomer of AB-polybenzimidazole (AB-PBI) was developed as a candidate for high-temperature polymer electrolyte membrane fuel cells. A diacid monomer, 2,2′-bisbenzimidazole-5,5′-dicarboxylic acid, was synthesized and polymerized with 3,3′,4,4′-tetraaminobiphenyl to prepare a polymer that was composed of repeating 2,5-benzimidazole units. In contrast to previously prepared AB-PBI, which contains only head-to-tail benzimidazole sequences, the new polymer also contains head-to-head and tail-to-tail benzimidazole sequences. The polymer was prepared in polyphosphoric acid (PPA) and cast into membranes using the sol-gel PPA process. Membranes formed from the new AB-PBI were found to be mechanically stronger, possessed higher acid doping levels, and showed improved fuel cell performance, when compared to the previously known AB-PBI.
Benzimidazole, Benzoxazole and Benzothiazole Derivatives, Optical Film Comprising them and Method of Producing thereof
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Page/Page column 15, (2010/12/29)
The present invention is relates to the synthesis of predominantly planar heterocyclic organic compound and the manufacture of optical films based on these compounds. Said organic compound has the general structural formula where Het is a predominantly planar heterocyclic molecular system possessing hydrophilic properties; B is a binding group; p is the number in the range from 3 to 8; S is a group providing solubility of the organic compound; m is a number in the range from 0 to 8. Said organic compound is transparent for electromagnetic radiation in the visible spectral range from 400 to 700 nm, and a solution of the compound or a salt thereof is capable of forming a substantially transparent optical layer on a substrate, with the heterocyclic molecular planes oriented predominantly parallel to the substrate surface.
