Thermodynamic properties of four alkyl imidazolium phosphate ionic liquids
The density,viscosity,and conductivity of 1-ethyl-3-methylimidazolium dihydrogen-phosphate([EMIM][DHP]),1-ethyl-3-methylimidazolium dimethylphosphate([EMIM][DMP]),1-ethyl-3-methylimidazolium diethylphosphate([EMIM][DEP])and 1-butyl-3-methylimidazolium dibutyl-phosphate([BMIM][DBP])ionic liquids were measured in the temperature range of 293.15K to 353.15K under ambient conditions.Some important volumetric properties,including the isobaric thermal expansion coefficients,molecular volume,standard entropy and lattice potential energy were calculated from the experimental density values.The thermal gravimetric analysis was performed in the temperature range of 35℃to 700℃,resulting in thermal decomposition temperatures up to 271.9-278.6℃.The Walden rule analysis demonstrated that four phosphate ionic liquids complied with the Walden rule well,while[EMIM][DMP]and[EMIM][DEP]were classified as"good ionic liquids".