Syntheses and photoluminescence properties of UV photocrosslinkable polyesters based on fluorene

Suppression of the green emission for polyfluorene has been widely investigated and various methods have been explored. In the present work, the photocrosslinkable copolyesters based on ferulic acid and 9-hydroxy-9-fluorene-carboxylic acid with different monomer feed molar ratios were synthesized and photocrosslinking reactions were employed to make the copolyesters crosslinked. All the photoluminescence spectra of the polyesters prior to photocrosslinking peaked at 418 nm in chloroform with quantum efficiencies more than 0.65. After crosslinking, copolyester P2 showed better thermo-stability of photoluminescence than the conjugated poly(9,9-dihexylfluorene). This indicated that the crosslinking architecture could suppress the chain aggregation, thus improving the purity of blue emission.