Preparation In Ionic Liquids, Properties And Applications Of Conducting Polymers

Conducting polymers have drawn much attention in recent years because of their extensive uses as conductors, electrode materials, and organic semiconductors etc. Among many conducting polymers, polythiophene(PTh) and polyaniline(PAn) are thought to be the most valuable organic macromolecules. Generally, polymers are prepared by means of two main routes i.e. the chemical and the electrochemical synthesis. Compared with chemical method, electrochemical way can control "doping" progress and the products are uniform and can be reversible redox reactions. Ionic liquids, a kind of novel environment-benign "green solvents" which can reduce pollution greatly, can be utilized repeatedly. So, the electrosynthesis of conducting polymers in ionic liquids is of great importance both theoretically and practically.We pay main attention to four points , first ,We polymerized aniline using electrochemistry methods in [BMIM]BF4, [BMIM]PF6 and [HMIM]BF4. Generally, the polymerization of aniline is carried out in acidic solution, and some are in ionic liquids, but ionic liquids they used are either haloaluminate anion which require strict condition, or liquids which acid are added to, we used three kinds of ionic liquids as solvent and electrolyte in electropolymerization of aniline, and the products had obvious responses in acidic solution, Among them, the polymerization rate is fastest in [HMIM]BF4.which is acidic, and the polymer film is active. Cation, anion and molecule can penetrate into film and cyclic voltammetric wave of these matters is observed. The peak current increased obviously so the film can be used in electroanalysis process.Second, We polymerized thiophene using electrochemistry methods in [BMIM]BF4, [BMIM]PF6 and [HMIM]BF4. Generally, the polymerization of thiophene is carried out in organic solution, and some are in concentrated acidic solution. We found that the polythiophene can be obtained in the three kinds of ionic liquids, but the result in [BMIM]PF6 is better than the others. The most of polymer was stable on 800 ℃ according to TA-TG. Catechol and hydroquione had cyclicvoltammetric wave in film electrode We observed electrochromic phenomenon. Finally we applied polythiophene to desulfur, we found that the longer electrolysis time and the higher the concentration was, the better the desulfiiration efficiency was. The optimum current density was different in different ionic liquids.Third, the polymerization of 3-methylthiophene was studied in [BMIM]PF6. It showed that the polymerization was satisfactory. The suitable potential was 1.4~2.3V and current was 0.5~6mA.cm~-2. The AFM showed us the fibre structure in "undoping" state ,while the "doping" state was more compact. The electrochromic phenomenon of the film was studied in ionic liquids and organic solvent.Fourth, The polymerization of aniline derivations such as p-phenylenediamine, dichloroaniline, benzidine, o-methylaniline was studied in [HMIM]BF4. The results were not satisfactory except o-methylaniline. The polymerization of benzothiophene, which is difficult to be got rid of, could be carried out in [BMIM]BF4 [HMIM]BF4.