Polyimides and polyamides with semiflexible spacers

Thirteen polyimides and three polyamides were synthesized with alternating rigid and semiflexible polymethylene units along the chain backbone. Derivatives of the pyromellitic species served as rigid segments in the polyimides and the sulfanilamide group was incorporated in the rigid segments of the polyamides. These systems were examined for a thermotropic liquid–crystalline phase. None was detected, probably because of the high crystalline melting temperatures of these polymers.