Synthesis and Electron Transporting Properties of Polyfluorene-graft-Polystyrene

Polyfluorene (PF) and its derivatives have been widely recognized as PLED materials with several advantages. To fulfill higher electron transporting properties, we incorporated polystyrene (PSt) at the active position of fluorene as side chain. Polyfluorene-graft-polystyrene (PF-g-PSt) was prepared with a different ratio of PSt side chain in the PF main chain. Compared with various properties of the homopolymer, it is found that that the graft polymers had similar thermal and electrochemical performance, less the beta-phase formation and photoluminescent stability, but smoother surface and higher crystallinity. Judging from the electron mobilities determined from the space charge limited current profiles, it was found that the graft polymer with one PSt side chain in main chain in average exhibited the higher electron mobility than the homopolymer and other graft polymers attached with more PSt side chains.