Preparation and properties of novel aromatic polyimides from 5,7-diamino-1,1,4,6-tetramethylindan and aromatic tetracarboxylic dianhydrides

Novel aromatic polyimides containing indan structure units were prepared fr om 5,7-diamino-1,1,4,6-tetramethylindan and various aromatic tetracarboxyli c dianhydrides. The glass transition temperatures (Tg's) of these polyimide s were not observed by differential scanning calorimetry at a temperature l ower than 500 degreesC and the 5% weight loss temperatures (T-d5's) of them were above 422 and 474 degreesC in air and nitrogen, respectively. Polyimi de prepared from 5,7-diamino-1,1,4,6-tetramethylindan and 2,2-bis(3,4-dicar boxyphenyl)1,1,1,3,3,3-hexafluoropropane dianhydride was soluble in organic solvents such as tetrahydrofuran, cyclopentanone, chloroform, acetone, eth yl acetate, N-methyl-2-pyrrolidinone and cresol at 20 wt% concentration at ambient temperature. The other resulting polyimides obtained from this diam ine possessing an indan structure were also soluble in several organic solv ents. These results indicated that polymer properties such as thermal behav iour and solubilities were influenced by the indan structure unit in a repe ating structure.