Abstract: 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]⁺.

Key words: 1-vinyl-3-alkylimidazole bromide, ionic liquids, electrolytes, conductivity

摘要： 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。

关键词: 溴化1-乙烯基-3-烷基咪唑, 离子液体, 电解质, 电导率