Polyimides Based on Norbornane-2,3,5,6-tetracarboxylic dianhydride

The polycondensation of norbornane-2,3,5,6-tetracarboxylic acid dianhydride with various diamines has been studied for the first time in order to synthesize new polyimides based on cycloaliphatic dianhydride. Norbornane-2,3,5,6-tetracarboxylic dianhydride (NBDA) has been synthesized from cis-5-norbornane-exo-2,3-dicarboxylic anhydride. The possibility of obtaining polyimides based on norbornane-2,3,5,6-tetracarboxylic dianhydride has been studied by carrying out synthesis under different conditions. Chloroform-soluble, film-forming polyimides based on norbornane-2,3,5,6-tetracarboxylic dianhydride have been obtained by one-step catalytic polycyclocondensation of norbornane-2,3,5,6-tetracarboxylic dianhydride with aromatic diamines in a benzoic acid melt. According to the second method, the polyimide based on norbornane-2,3,5,6-tetracarboxylic dianhydride has been produced using a two-step procedure: low-temperature polycondensation of silylated cycloaliphatic diamine (N,N′-bis(trimethylsilyl)isophoronediamine) in an amide solvent to form a soluble prepolymer with its subsequent imidization in the solid phase. The heat treatment conditions have been optimized for the prepolymer, allowing the production of a polymer with a composition corresponding to the target polyimide. The obtained polymers have been characterized by IR spectrometry, ¹H NMR and solid-state ¹³C NMR spectroscopy, elemental analysis, and DSC and TGA techniques.