Properties of Polyaniline Synthesized in Ionic Liquid (1-Ethyl-3-methylimidazoliumethyl sulphate)

The electroactive polyaniline at high pH was electrochemically synthesized in a solution containing 0.2 mol.dm-3 aniline and ionic liquid, 1-ethyl-3-methylimidazolium- ethyl sulphate (EMIES). The cyclic voltammograms of the polyaniline were performed in 1.0 mol.dm-3 KCl in a range of pH from 8.0 to 12.0 between 0.0 and 1.2 V at 60 mV.s-1. The results indicated only 14.4% decay of the electrochemical activity when the polyaniline was moved from pH 8.0 to 10.0. The polyaniline still retains good electrochemical activity at pH 12.0. The results of UV-visible and FTIR spectrum reveal that the framework of polyaniline synthesized in EMIES is similar to that of polyaniline synthesized in HCl. The thermal behaviour of the polyaniline prepared in EMIES shows a three-step weight loss process, they are at about 100ºC, 200- 300ºC and over 350ºC, respectively. The conductivity of polyaniline synthesized in EMIES is 0.011 S.cm-1. After immersion of polyaniline into 1.0 mol.dm-3 HCl or 1.0 mol.dm-3 KCl for one hour, its conductivity enhances to 0.53 or 0.052 S.cm-1, respectively. Based on the results of osmometry, the average molecular weight of the polyaniline is about 4.97×104. The polyaniline can be dissolved in DMF and other common organic solvents but little in water, which is very favourable to structural analysis and applications of polyaniline.