Synthesis and characterization of novel carbazole-containing soluble polyimides

Three new carbazole-based diamines, 3,6-diaminocarbazole (2), 3,6-diamino-N-phenylcarbazole (4) and N-(4'-aminophenyl)-3'-aminophenyl (7), were prepared from carbazole or N-phenylcarbazole. Homopolyimides and copolyimides derived from these three diamines as well as 4,4'-diamineodiphenyl ether (DDE), with 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) in 1-methyl-2-pyrrolidinone (NMP) via a two-step condensation reaction, were obtained. These polyimides, especially those derived from monomers 4 and 7, were readily soluble in many organic polar solvents. They had weight-average molecular weights ranging from 1.5 x 10(4) to 5.9 x 10(4). DSC analyses indicated that (co)polyimides derived from diamine 4 had glass transition temperatures and others derived from diamines 2 and 7 did not show any glass transition prior to thermal decomposition in air.