Heat-resistant resins obtained from polymer precursors bearing β,β′-dicyanovinyl terminal groups

Certain polymer precursors of the general formula: where A is an aromatic structure bearing ester, amide, azomethine, or imide linkages were synthesized. Particularly, 4-hydroxybenzaldehyde was condensed with malonitrile to afford 4-hydroxy-β,β′-dicyanostyrene which reacted with a half molar amount of terephthaloyl dichloride in the presence of an acid acceptor. In addition, 3-nitrobenzaldehyde was condensed with malonitrile to yield 3-nitro-β,β′-dicyanostyrene that was catalytically hydrogenated to the corresponding amine. The latter reacted with a half molar amount of terephthaloyl dichloride, terephthaldehyde, pyromellitic dianhydride, or benzophenone tetracarboxylic dianhydride. The polymer precursors were characterized by elemental analyses as well as IR and ¹H-NMR spectroscopy. Their curing behavior was investigated by DTA. Crosslinked polymers were obtained by curing the monomers at 300°C for 24 h. They were stable up to 407–437°C in N₂ and afforded an anaerobic char yield of 65–50% at 800°C. The thermal stability of resins was correlated with their chemical structures. © 1993 John Wiley & Sons, Inc.