New polymaleamides from N,N'-ethylenedianilinobisisomaleimide and aromatic diamines by ring-opening polyaddition: Synthesis and characterization

Polymaleamides have been synthesized by the ring-opening polyaddition of N,N'-ethylenedianilinobisisomaleimide (EBIMI) with the aromatic diamines, 4,4'-diaminodiphenylmethane, 4,4'-diaminobibenzyl, 4,4'-diaminodiphenylsulfone, 1,5-diaminonaphthalene, and 2,4-diaminopyridine in 1-methyl-2-pyrrolidinone. The appropriate model compound was also prepared. The structures of EBIMI, the model compound, and the polymaleamides were confirmed by IR, UV-Vis, H-1-NMR spectra, and elemental analyses. The IR spectra revealed the retention of cis-geometry about the C=C bonds in EBIMI and in the polymaleamides. The polymers were characterized by inherent viscosity, solubility, thermal stability, and DSC measurements. The polymaleamides were found to have inherent viscosities in the 0.06-0.13 dL/g range. The polymers were completely soluble in concentrated sulfuric acid and were found to be insoluble in organic solvents such as ethyl alcohol and acetone. The thermal degradation behaviors of the polymaleamides were studied by mass spectrometry; proposed fragmentation schemes for the polymaleamides are discussed.