Polymaleamide-polymaleimide networks were obtained as films by the thermal treatment of mixtures with different ratios of an aliphatic-aromatic polymaleamide (PMA) and 4,4'-bis(maleimidodiphenylmethane) (BMI), in N-methyl-2-pyrolidinone (NMP) as a solvent. The polymaleamides were synthesized by ring-opening polyaddition of 1,6-hexamethylene-bisisomaleimide with 4,4'-diaminodiphenylmethane in NMP at room temperature. The networks are infusible and insoluble in organic solvents; therefore, they were studied by solid-state techniques such as IR, DSC, thermooptical analysis (TOA), TG/DTG analysis, and TEM. Thermal treatment of pure PMA and BMI occurs with the formation of crosslinked structures as proved by IR spectra. DSC and TOA curves show the appearance of chemical interactions between PMA and BMI in cured films and the formation of ordered morphologies, especially when BMI is the major component. TG/DTG and TEM results supported these observations. The PMA-polymaleimide network films present electrical insulator properties superior to individual polyamides or polyimides. (C) 2003 Wiley Periodicals, Inc.