Preparation and properties of novel aromatic polyimides from 4,4 '-diamino-4 ''-hydroxytriphenylamine and aromatic tetracarboxylic dianhydrides

Novel aromatic polyimides containing hydroxytriphenylamine units were prepa red from 4,4'-diamino-4 "-hydroxytriphenylamine 1 and various aromatic tetr acarboxylic dianhydrides 2. The glass transition temperatures (T(g)s) Of th ese polyimides were in the range of 274-388 degrees C and the 10% weight lo ss temperatures (Td(10)s) were above 462 and 511 degrees C in air and nitro gen respectively. Polyimide 4f prepared from diamine 1 and 4,4'-hexafluoroi sopropylidenebis(phthalic anhydride) (6FDA) was soluble not only in organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimeth ylformamide, 1,3-dimethyl-2-imidazolidone and dimethyl sulfoxide but also i n tetramethylammonium hydroxide aqueous solution. Other resulting polyimide s were not soluble in organic solvents. The resulting polyimides 4 possesse d T(g)s about 20-70 degrees C higher and poorer solubilities than the previ ously reported polyimides prepared from 4,4'-diaminotriphenylamine and vari ous aromatic tetracarboxylic dianhydrides. These results indicated that pol ymer properties such as thermal behaviour and solubilities were influenced by the intermolecular interaction of hydrogen bonding due to hydroxy units.