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]+.