ELECTROCHEMICAL POLYMERIZATION OF FLUORENE IN MIXED PROTON ELECTROLYTE OF ACETIC ACID CONTAINING BORON TRIFLUORIDE DIETHYL ETHERATE

Abstract

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.