四种烷基咪唑磷酸酯离子液体的热力学性质

Thermodynamic properties of four alkyl imidazolium phosphate ionic liquids

针对烷基咪唑磷酸酯离子液体的热物性数据较少的问题,本文在常压下测定了1-乙基-3-甲基咪唑磷酸二氢盐([EMIM][DHP])、1-乙基-3-甲基咪唑磷酸二甲酯盐([EMIM][DMP])、1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM][DEP])、1-丁基-3-甲基咪唑磷酸二丁酯盐([BMIM][DBP])四种烷基咪唑磷酸酯离子液体的密度、黏度(293.15~353.15K)和电导率(293.15~343.15K),并且测定了四种离子液体的热稳定性。结果表明,离子液体的密度、黏度随温度的升高而减小,而电导率随温度的升高而增大。采用自然对数方程关联四种离子液体的密度,根据实验值计算到了离子液体体积性质;采用VFT方程关联离子液体黏度和电导率,其中密度与电导率的实验值与模型相关系数R2达到0.9999,黏度相关系数R2达到0.99999,实验测定的数据与模型一致;四种离子液体的热稳定性相近,分解温度均在271.9~278.6℃范围内;瓦尔登规则分析表明,四种烷基咪唑磷酸酯离子液体符合Walden规则,而[EMIM][DMP]和[EMIM][DEP]被归类为“good ionic liquids”。

The density,viscosity,and conductivity of 1-ethyl-3-methylimidazolium dihydrogenphosphate([EMIM][DHP]),1-ethyl-3-methylimidazolium dimethylphosphate([EMIM][DMP]),1-ethyl-3-methylimidazolium diethylphosphate([EMIM][DEP])and 1-butyl-3-methylimidazolium dibutylphosphate([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”.