Synthesis and Characterization of New Functional Bismaleimides

Functional bismaleimides containing γ-lactone, carboxyl, aldehyde, hydroxyl, azomethine or cinnamoyl groups were synthesized from maleimido benzoic acid via its acid chloride with phenolphtaleine, 5,5′-methylene-bissalicylic acid, 5,5′-methylene-bissalicylaldehyde, glycerol, tartaric acid and 3,4-bis(hydroxyethan-2-tioether)- p-maleimidobenzoic acid, by simple condensation or polymer analogous reactions on some of these reactive bisimides. The monomers were characterized by IR, 1 H-NMR and elemental analysis. The DSC curves of all the samples showed an exotherm in the temperature range of 134–310 °C, which is attributable to curing reactions. Thermogravimetric analysis of the uncured resins indicated good thermal stability and a char yield of bismaleimide resins in accordance with the calculated C/H ratio. Their relative thermoxidative stability was evaluated by isothermal gravimetric analysis.