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A series of stable diaminobisimides (DABIs) has been prepared as alternatives to simple aromatic diamines for use in the preparation of condensation polymers. These DABIs were prepared by reacting two moles of an aromatic diamine with one mole of a dianhydride under conditions that minimize side reactions and the formation of oligomers. In many cases, the pure DABI consisting of two moles of the diamine and one mole of the dianhydride (i.e. the 2:1 product) can be obtained free of oligomers (i.e. the 3:2, 4:3 etc products). The studies have shown that the major factor determining the yield and purity of a DABI is the extent of conjugation between the two amino groups in the starting diamine: to a lesser extent steric effects in the diamines also influence the product composition. The reaction conditions necessary to produce these new DABIs are described together with extensive characterization of these materials by FTIR,1H and 13C NMR and gel permeation chromatography. The results indicate that pure DABIs are more manageable materials than the impure. insoluble materials previously described in the literature and can be used successfully to produce useful high-temperature stable polymers.

New bismaleimide monomers, based on pure diaminobismides (DABIs) have been synthesized. In a number of cases the bismaleimide of the 2:1 (amine/anhydride) DABI adduct has been isolated as a pure compound, but where the starting DABI consisted of a mix of imide oligomers of the diamine and dianhydride (2:1, 3:2 and higher) the corresponding bismaleimide product was found also to have a similar composition ratio. This has been confirmed in one example by separation of the oligomer mix and characterization of the components. The utility of the various bismaleimides as monomers in composite matrices has been assessed by cocuring with the common coreactant, 3,3′-diallylbisphenol A. The physical properties and thermal stability of neat resin samples and laminates are reported as well as some mechanical properties.