Preparation of polyimides utilizing the diels–alder reaction. I. Bis(3,4-dimethylenepyrrolidyl) arylenes with bismaleimides

Bis(exocyclic)dienes were prepared by the reaction of 2,3-dibromomethyl-1,3-butadiene with aromatic diamines. The diamines were 4,4′-methylene dianiline, 4,4′-oxy dianiline, benzidine, and α, α′-bis(4-aminophenyl)-p-isopropyl benzene (EPON HPT 1061). Polymers were synthesized by the Diels–Alder reaction of these bisdienes with bis(4-maleimidylphenyl) methane. Flexible films were obtained for diene: dienophile ratios ranging from 0.7 : 1 to 0.8 : 1. Films were found to be insoluble in organic solvents and those cured above 120°C were insoluble in concentrated sulfuric acid. The polymers were characterized by IR, TGA, and elemental analysis.