Abstract: An improved synthesis for PMR-type polyimides, including first preparing a dimer of 5-norbornene-2,3-dicarboxylic acid, or acid ester or anhydride and 4,4'methylene dianiline. This dimer is then reacted with one of the following:1. the reaction product of a primary aromatic diamine and an aromatic dianhydride.2. an aromatic dianhydride.3. a mixture of a primary aromatic diamine and an aromatic dianhydride, or an ester of an aromatic tetraacid or an aromatic tetraacid.The resulting polyimide prepolymer exhibits superior physical properties and is substantially free of undesired impurities and unreacted 4,4'-methylene dianiline.

Abstract: An improved synthesis for PMR-type polyimides, including first preparing a dimer of 5-norbornene-2,3-dicarboxylic acid, or acid ester or anhydride and 4,4'methylenedianiline. This dimer is then reacted with the reaction product of the dimethyl ester (or dianhydride) of 3,3', 4,4'-benzophenonetetracarboxylic acid and 4,4'-methylenedianiline. The resulting polyimide prepolymer exhibits superior physical properties and is substantially free of the undesired trimer of 5-norbornene-2,3-dicarboxylic acid, or acid ester or anhydride and 4,4'-methylenedianiline. When this dimer is reacted with 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride methylenedianiline amic acid mixture, the resulting polyimide prepolymer exhibits superior physical properties.