Preparation of Optically Active Polyimides Based on 2,2-diamino-1,1-binaphthalene

Linear polyimides based on both of the 2,2 '-diamino-1,1 '-binaphthalene enantiomers and their racemic mixture were synthesized and characterized. A two-step synthetic route, consisting of the preparation of the polyimide precursor followed by its thermal imidization at temperatures not exceeding 200 degrees C, was employed. The products were analyzed by FTIR and H-1 NMR spectroscopy. All of the tested materials were nearly fully imidized after 25 h. The final polyimides possess high glass transition temperatures, are thermo-oxidatively stable and are soluble in common organic solvents as 1-methyl-2-pyrrolidone, tetrahydrofuran and chloroform; additionally, those prepared from the enantiomers show optical activity. The values of specific optical rotations for the polymers were higher than those for the corresponding monomers. However, the directions of their optical rotations were identical. Due to their rather low molar masses, the final polyimides form brittle self-standing films. Thin layers of these products on porous polyimide substrates were made under forming composite membranes.