Polybenzimidazole synthesis

Scheme 14. Two-stage polybenzimidazole synthesis from 33 -diaminobenzidine and aromatic dialdehydes...

Scheme 18. Polybenzimidazole synthesis, exemplified by the polycondensation of 2,6-dimethyl-imidazo[4,5-/lbenamidazole with terephthalaldehyde...

Scheme 9. Polybenzimidazole synthesis from diaminobenzidiiie and diacetylbenzene...

Scheme 11. Polybenzimidazole synthesis from tetraaminobenzene and bisulfite adduct of isophthalaldehyde...

E.W. Neuse, M.S. Loonat, Two-stage polybenzimidazole synthesis via poly(azomethine) intermediates. Macromolecules 16 (1) (1983) 128-136. 

Hedberg EL, Marvel CS (1974) A new single-step process for polybenzimidazole synthesis. J Polym Sci 12 1823-1828... 

Hu M, Pearce EM, Kwei TK (1993) Modification of polybenzimidazole synthesis and thermal stability of poly(Nl-methylbenzimidazole) and poly(Nl, N3-dimethylbenzimidazolium) salt. J Polym Sci A 31 553-561... 

Kumbharkar SC, Kharul UK (2009) JV-substitution of polybenzimidazoles synthesis and evaluation of physical properties. Eur Polym J 45 3363-3371... 

PBI is being marketed as a replacement for asbestos and as a high temperature filtration fabric with exceUent textile apparel properties. The synthesis of whoUy aromatic polybenzimidazoles with improved thermal stabUities was reported in 1961 (12). The Non-MetaUic Materials and Manufacturing Technology Division of the U.S. Air Force Materials Laboratory, Wright-Patterson Air Force Base, awarded a contract to the Narmco Research and Development Division of the Whittaker Corp. for development of these materials into high temperature adhesives and laminates. 

PA-4,6 synthesis from, 171-172 PA-6,6 polymerization from, 169-170 PA-6,1 synthesis from, 181 PA salt solution, polymerization from, 164 Pawlow, James H., 431 PBIs. See Polybenzimidazoles (PBIs)... 

Poly(arylene thioether)s, 363-364 Poly(arylene thioether sulfone)s, 364 Poly(aryl sulfone) derivatives, 354 Poly(p-benzamide), synthesis of, 188-189 Polybenzimidazoles (PBIs), 265 ferrocene-containing, 315 synthesis of, 313... 

Polyazo dyes, 9 363—361 Polybenzamide, 15 109-110 Poly(p-benzamide) (PBA), 10 212 19 714 crystal lattice parameters of, 19 728t laboratory synthesis of, 19 719 Polybenzimidazole (PBI), asbestos substitute, 3 3141 Polybenzimidazole (PBI) fibers,... 

Sulfonation of polybenzimidazole was also accomplished by proton abstraction with an alkali metal hydride followed by reaction with sodium (4-bromomethyl)benzenesulfonate. The degree of sulfonation in this synthesis can be controlled by the... 

Considerable efforts have centered on carrying out the synthesis of polybenzimidazoles at more moderate temperatures. Polymerization of the isophthalic acid or its diphenyl ester have been successfully carried out in polyphosphoric acid or methanesulfonic acid-phosphorous pentoxide at 140-180°C, but the reaction is limited by the very low solubilities (<5%) of the reactants in that solvent. The lower reaction temperature is a consequence of activation of the carboxyl reactant via phosphorylation. Lower reaction temperatures are also achieved in hot molten nonsolvents such as sulfolane and diphenyl sulfone, but the need to remove such solvents by a filtration or solvent extraction is a disadvantage. 

Stepwise addition polymerisation (polyaddition) or condensation polymerisation (polycondensation) are possible polyreactions for the first step. The two latter combinations attained interest in the technical synthesis of polyimides and polybenzimidazoles. 

Much attention has been paid to the synthesis of fluorine-containing condensation polymers because of their unique properties (43) and different classes of polymers including polyethers, polyesters, polycarbonates, polyamides, polyurethanes, polyimides, polybenzimidazoles, and epoxy prepolymers containing pendent or backbone-incorporated bis-trifluoromethyl groups have been developed. These polymers exhibit promise as film formers, gas separation membranes, seals, soluble polymers, coatings, adhesives, and in other high temperature applications (103,104). Such polymers show increased solubility, glass-transition temperature, flame resistance, thermal stability, oxidation and environmental stability, decreased color, crystallinity, dielectric constant, and water absorption. 

Xiao, L. et al.. Synthesis and characterization of pyridine-based polybenzimidazoles for high temperature polymer electrolyte membrane fuel cell applications. Fuel Cells, 5, 287, 2005. 

Glipa, X. et al.. Synthesis and characterisation of sulfonated polybenzimidazole a highly conducting proton exchange polymer. Solid State Ionics, 97, 323, 1997. 

Several years ago, encouraged by the proven intermediacy of polyimidazolines in Gray s imidazole polymer synthesis we set out to demonstrate experimentally an analogous intermediary stage in the polycondensation of Scheme 13 and develop a preparative approach that would enable us to isolate soluble polyimidazoline intermediates. Clearly, if such polymeric imidazolines could be isolated and their further smc th conversion to polybenzimidazoles be accomplished, the door would be opened for the development of two-stage processing techniques involving prepolymer-type materials. Initial... 

Lixiang, X. Zhang, H. Choe, E.-W. Scanlon, E. Ramanathan, L.S. Benicewicz, B.C. Synthesis and characterization of pyridine-based polybenzimidazoles as novel fuel cell membrane materials. Fuel Chem. Div. Prepr. 2003, 48, 447. 

Unlike polybenzimidazole-based thermo-oxidatively stable supports, polyimides can be prepared under relatively mild conditions from starting materials of only low or modest cost [7,8], Polyimide particulates were prepared in a bead form without functional [9,10], We now report the synthesis of functional polyimide beads and their use as epoxidation catalyst supports. The presence of the functional group in the polyimides allows further chemical exploitation, particularly as a catalyst support capable of operating under rather severe oxidative conditions. 

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