Synthesis of blue emitting alicyclic polyimides using one-pot alternating copolymerization method

A series of alternating copolyimides (altPIs) having highly blue fluorescing 9,10-diphenyl-anthracene units were synthesized and the photoluminescence of the altPIs were investigated. The alt-PIs were prepared by sequential addition of two diamines to a solution of spiroalicyclic tetracarboxylic dianhydride, rel[1R,5S,6R]-3-oxabicyclo[3.2.1]octane-2,4-dione-6-spiro-3 - (tetrahydrofuran-2-,5 - dione) (DAn), on the basis of the unique regioselective ring opening reactivity of DAn to the aromatic amines. The alternating structure of the polyimides was confirmed by comparison of its 1H NMR with that of the corresponding random counterparts. The altPIs showed glass transition temperature higher than 240°C. A 5% weight loss temperature was in a range of 335 to 376°C. The polyimides showed blue fluorescence (_max = 435 to 436 nm) in DMSO solution with a fluorescence quantum yield of 0.64 to 0.77. In the film state, although small red shift was observed compared to the solution state, the altPIs gave blue emission (_max = 437 to 447 nm).