Synthesis of polybenzimidazoles containing arylene sulfone and ether linkages

Graduation date: 1993Polybenzimidazoles were synthesized from 3,3'-diaminobenzidine (DAB) and dicarboxylic acids. The polymerizations using the dicarboxylic acid monomers were carried out in polyphosphoric acid (PPA) and phosphorus pentoxide/methansulfonic acid (PPMA) which acted as the solvent and condensing agent. The resulting polybenzimidazoles had inherent viscosities in the range of 0.12 to 0.84 dL/g. The products were generally of low molecular weight as indicated by low inherent viscosities. The products of the dicarboxylic acid monomers and DAB having the highest inherent viscosities and forming strong, flexible films were formed in the polymerizations using the purest monomers. The dicarboxylic acid monomers were synthesized to contain internal sulfonate and ether linkages which were intended to increase the flexibility and processibility of the resulting polymers. These monomers can be used in the preparation of several other types of polymers such as polybenzoxazoles and polybenzothiazoles