Isomeric bismaleimides and polyaspartimides

The properties of a series of bismaleimides and polyaspartimides synthesized from the 3,3', 3,4', and 4,4' isomers of diaminodiphenylmethane are described and compared. The effects of the amine isomerism on the characteristics of bismaleimides and their polymers are investigated. It is observed that the 3,3'-bismaleimide had the highest crystalline melting point, the 4,4' isomer the lowest, and the 3,4'-bismaleimide was slightly above the all-para compounds; for the polyaspartimides, the all-para combinations had the highest glass transition temperature (218 C) and the all-meta the lowest (168 C). The data reveal that strong, flexible films were obtained only from the polyaspartimides made from the 4,4'-diamine/4,4'bismaleimide and the 3,4'-diamine/3,4'bismaleimide combinations; and the tensile properties of the 3,4'polymer films were as good as those of the 4,4 'polymer.