溴化1-乙烯基-3-烷基咪唑离子液体的电化学性能

Electrochemical properties of 1-vinyl-3-alkylimidazole bromide ionic liquids

合成了溴化1-乙烯基-3-烷基咪唑（[VAIM]Br）离子液体,采用FTIR、1H NMR、TG及DSC进行了表征,并系统研究了[VAIM]Br的电化学性能。结果表明：在298.15～323.15 K内,[VAIM]Br的电导率（σ）与温度符合Arrhenius方程,电导活化能随[VAIM]＋上烷基链的增长而降低。分别以水、甲醇和乙醇为溶剂的[VAIM]Br溶液的电导率均随浓度的增大而显著增大,且σ（水）〉σ（甲醇）〉σ（乙醇）。通过电导法确定了[VAIM]Br在水、甲醇、乙醇中的临界胶束浓度,分别约为6.8×10-6、1.5×10-5、2.0×10-5 mol·L-1,表面活性优异。[VAIM]Br的电化学窗口在1.6～2.5 V,其电化学稳定性随[VAIM]＋上烷基链的增长而逐渐降低。

Ionic liquids 1-vinyl-3-alkyl imidazolium bromide（[VAIM]Br）were synthesized and characterized by FTIR,1H NMR,TG and DSC,and their electrochemical properties were studied.The results indicated that the temperature dependence of conductivity（σ）obeyed Arrhenius type equation at a range from 298.15 K to 323.15 K and the activation energy for conductivity decreased with the extension of the alkyl chain of the[VAIM]＋.The conductivities of[VAIM]Br solutions using water,methanol or ethanol as solvents respectively all increased remarkably with the increasing concentration of[VAIM]Br,and corresponded to σ（water）〉σ（methanol）〉σ（ethanol）.The critical micelle concentrations of the[VAIM]Br in different solutions were confirmed by conductance method which were about 6.8×10-6 mol·L-1 in water,1.5×10-5 mol·L-1in methanol and 2.0×10-5 mol·L-1 in ethanol respectively.This showed superior surface activities of[VAIM]Br.Electrochemical window of[VAIM]Br were from 1.6 V to 2.5 V,and electrochemical stability decreased with the extension of the alkyl side chain of[VAIM]＋.