POLY(ARYL ETHER BENZIMIDAZOLES)

A method for the preparation of poly(aryl ether benzimidazoles) has be en developed where the generation of an ether linkage is the polymer-f orming reaction. We found that 2-(4-fluorophenyl)-benzimidazoles were activated toward nucleophilic aromatic substitution with phenoxides. F acile displacement occurred at this position since the benzimidazole r ing can stabilize the negative charge developed in the transition stat e through a Meisenheimer complex, analogous to conventional activating groups (e.g., sulfone or carbonyl). An appropriately substituted diha lo bibenzimidazole, 2,2'-bis(4-fluorophenyl)-6,6'-bibenzimidazole, was prepared and polymerized with bisphenols in aprotic dipolar solvents in the presence of K2CO3. High molecular weight polymers were obtained with glass transition temperatures ranging from 220 to 250 degrees C. The resulting polymers were processable from solution and showed good thermal stability. This general synthetic route was also applied to A B monomers which, once polymerized, produced high polymer. This synthe tic route affords the poly(benzimidazole) analogue of poly(ether imide ) and shows many of the same desirable characteristics.