Polyfluorene flims were synthesized electrochemically by direct anodic oxidation of fluorene in the mixed electrolyte of acetic acid and borontrifluoride diethyl etherate (BFEE) (5∶4 by volume).The oxidation potential of fluorine in the mixed electrolyte was measured to be only 0.48 V versus Pt

which was much lower than that determined in acetonitrile containing 0.1 mol L-1 tetrabutylammonium tetrafluoroborate (TBATFB).The conductivity of polyfluorene from this medium was 0.5 S cm-1

which was higher than that determined in pure BFEE (0.25 S cm-1).The polyfluorene films obtained from acetic acid and BFEE (5∶4 by volume) showed good electrochemical behavior and stability in concentrated sulfuric acid.FTIR

1H\|NMR spectral results and theoretical studies demonstrated that the electropolymerization of fluorene mainly occurred at the 2

7-positions.Compared with that obtained from the mixed electrolyte without PEG1000

the polymer obtained from acetic acid and BFEE (5∶4 by volume) with PEG1000 showed a red shift in the fluorescence spectra

a better thermal stability and a more ordered stack of the platelet in appearance

but the thermal stability of the polymer obtained from acetic acid and BFEE (5∶4 by volume) was better than that for the one made in pure BFEE.At the same time

the fluorescence spectra results indicated that the soluble polyfluorene electrosynthesized from acetic acid and BFEE (5∶4 by volume) was a good blue light emitter which may find application in optoelectronics.