Conductive Polyaniline In Ionic Liquid Synthesis And Applications

1. Properties of polyaniline Synthesized in Ionic Liquid (EMIES)The electroactive polyaniline in the wide pH range was reported with electrochemical synthesis in the ionic liquid, 1-ethyl-3-methylimidazolium-ethyl sulfate (EMIES), containing 0.2 mol dm-3 aniline. The cyclic voltammograms of the polyaniline showed that the electrochemical activity of the polyaniline was only 22.4% decreased compared in 1.0 mol dm-3 KCl (pH 12.0) with in 1.0 mol dm-3 HCl. Based on structure analysis of FTIR and UV-vis spectra, the framework of the polyaniline synthesized in EMIES solution is similar to that of polyaniline synthesized in the HCl solution. The conductivity of polyaniline synthesized in EMIES is 1.08×10-2 S cm-1. However, after the polyaniline was immerged in1.0 mol dm-3 HCl and 1.0 mol dm-3 KCl (pH 6.9) for an hour, the conductivities of polyaniline rose to 5.30×10-1 and 5.20×10-2 S cm-1, respectively. The polyaniline synthesized at the condition can be dissolved in DMF and common organic solvents but hardly done in water.2. Effects of Ionic Liquid on Characteristics of PolyanilineThe electroactive polyaniline at high pH was electrochemically synthesized at 0.90 V in an aqueous solution containing 0.60 mol dm-3 aniline, 1.20 mol dm-3 1-ethyl-3-methylimidazolium-ethyl sulfate (EMIES) and 2.0 mol dm-3 H2SO4. The cyclic voltammograms of the polyaniline are similar to that of the control polyaniline synthesized in 2.0 mol dm-3 H2SO4. The result shows that two pairs of the redox peaks appeared on the cyclic voltammograms of the polyaniline in the solution of pH 6.0 at 60 mV s-1 and that the electrochemical activity only dropped 24.8% when the polyaniline was moved from pH 7.0 to 12.0. The conductivity of the polyaniline is 5.20 S cm-1, while that of the control polyaniline is only 0.62 S cm-1. UV-visible and FTIR spectrum reveal that the framework of the polyaniline is similar to that of the control polyaniline. The average molecular weight of the polyaniline is about 4.56×104 based on the results of osmometry. It is noticeable that the polyaniline can be well dissolved in DMF and common organic solvents but hardly done in water, which is very favorable to structural analysis and applications of the polyaniline.3. Study on Zn-polyaniline BatteryA Zn-polyaniline battery was consisted of polyaniline synthesized in 1-ethyl-3-methylimidazolium-ethyl sulfate (EMIES), Zn sheet and an electrolyte containing 2.0 mol dm-3 ZnCl2 and 3.0 mol dm-3 NH4Cl with pH 6.0. The battery was charged and discharged between 0.80 and 1.60 V at different current densities. The capacity and energy densities of polyaniline are 141.2 A h kg?1 and 169.2 W h kg?1 for discharge process at 0.5 mA cm-2, respectively, which are much better than those of the control polyaniline at the same condition. After the test of the charge–discharge at different current densities, the battery was successively charged and discharged for 150 cycles. The columbic efficiency of charge and discharge is 95.5% at 150th cycle, and the energy density of the battery is only lower 6.0% at 150th cycle than at 1st cycle.