Bisdichloromaleimide-amine polymers

Cross-Linking Reactions of Polymers. Bisdichloromaleimide-amine polymers contain (a) a double bond in the maleimidyl group, (b) chlorine, and (c) secondary amine group (-NH-). It may be possible to cross-link them either by the opening of the double bond (thermal polymerization) or by the nucleophilic displacement of chlorine by the secondary amine. The representative reaction scheme for such reactions is shown in Figure 6. The extent of such reactions may be evaluated by solubility measurements in dimethyIformamide. 

Relies and Schluenz (8) have reported the preparation of poly(maleimide-ethers) by using bisphenols and bisdichloromaleimides. These polymers were soluble in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) and gave tough flexible films. Phosphorus-containing poly(maleimide-amines) have been reported to have poor thermal stability and little flame retardation (9). 

Nucleophilic substitution reactions have been effectively exploited in the synthesis of several classes of polymers. However, only scanty reports are available on the application of such reactions to the displacement of chlorine in bisdichloromaleimides, although several examples of displacement of chloride by nucleophiles in N-substituted dichloromaleimides exist in literature. Amines (5), phenols (6), and alcohols and thiols (7) have been used as nucleophiles in such reactions. 

The reaction of diamines and bisdichloromaleimides proceeds with the displacement of one chlorine. The resulting poly(maleimide-amine) contain double bonds as well as chlorine in the backbone. The presence of double bonds in the backbone of these polymers also makes them susceptible to cross-linking reactions which may be initiated by heat. 

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