Electrochemical Synthesis Of Boron Trifluoride Diethyl Ether / Acetic Acid In The Conductive Polymer

The studies of conducting polymers were mainly concentrated on the simple heterocyclic polymers in the past 30 years,such as polypyrrole,polythiophene and its derivatives,etc.In recent years,high-quality conducting polymers prepared from fused ring aromatic compounds had attracted great attention.Electrosyntheses of conducting polymers has been tested as one of the most effective way.The electrochemical syntheses of conducting polymers were usually performed in neutral organic solvents or in aqueous solution.In these media,however,the oxidation potentials of many aromatic monomers were so high that they cannot be polymerized or the qualities of as-formed polymers were poor.Research suggests that high quality conducting polymer can be easily electrochemically synthesized in boron trifluoride diethyl etherate(BFEE), a middle strong Lewis acid,and BFEE based mixed electrolytes.This dissertation focused on the electropolymerization of carbazole,indole and its derivatives and fluorene in a novel mixed electrolyte of acetic acid and BFEE,and characterizations of these polymers.1.Carbazole was electropolymerized successfully in acetic acid containing 26%BFEE and 5%poly(ethylene glycol)(PEG) with molar mass of 400(by volume).The oxidation potential of carbazole in this medium was measured to be only 0.89 V.Polycarbazole films obtained from this medium showed good electrochemical behavior.FT-IR,¹H NMR and theoretical studies showed that the polymerization of carbazole mainly occurred at the 3,6-positions.The fluorescence spectra implied that polycarbazole obtained from this medium was a good blue-light emitter,and it may find application in OLED.Thermal study suggested the polymer has a good thermal stability and the maximal decomposition rate is located at 673 K.2.The electrochemical polymerizations of indole and its 5-position-substituted derivatives in the mixed electrolyte of acetic acid and BFEE(1:1 by volume) containing 0.005 mol Ll PEG1000 were tested.We found that the polymerizations of indole,5-cyanoindole,5-nitroindole, indole-5-carboxylic acid,and 5-methoxyindole were successful while those of 5-methylindole and 5-hydroxyindole were on the contrary.The electron-donating groups at 5-position inhibit electropolymerization;whereas the electron-withdrawing groups at 5-position allow the monomer to electropolymerization.These polymers all showed good redox properties and electrochemical stability in CH₂Cl₂ + 0.1 mol L^-1 Bu₄NBF₄ and concentrated sulfuric acid.FT-IR, ^-1H NMR spectral results and theoretical studies demonstrated that the electropolymerizations of indoles mainly occurred at the 2,3-positions.The fluorescence spectra indicated these polymers are blue-light-emitters.Furthermore,polyindole,poly(indole-5-carboxylic acid) and poly(5-cyanoindole) showed favorable photoluminescence properties.Thermogravimetric analysis suggested the better thermal stability of polyindole,poly(5-cyanoindole),and poly(5-nitroindole) compared with the worse of poly(5-cyanoindole) and poly(5-methoxyindole).3.High-quality polyfluorene flims were synthesized electrochemically by direct anodic oxidation of fluorene in the mixed electrolyte of acetic acid and BFEE(5:4 by volume).The polyfluorene films obtained from this medium showed good electrochemical behavior and stability in concentrated sulfuric acid.FT-IR,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 the mixed electrolyte with PEG1000 showed a red shift in the fluorescence spectra,a better thermal stability and a more ordered stack of the platelet in appearance.