Abstract:

The ionic liquids 1-ethyl-3-methylimidazolium methyl phosphonate ([Emim][OMP]) and 1-ethyl-3-methylimidazolium ethyl phosphonate ([Emim][OMP]) were synthesized and characterized by nuclear magnetic resonance and elemental analysis. The thermal stability, phase behavior, density and viscosity (293.15—353.15K), and conductivity and surface tension (293.15—343.15K) were measured at atmospheric pressure, and correlated with established empirical equations. Some thermophysical properties such as the isobaric thermal expansion coefficients, molecular volume, standard entropy and lattice potential energy were determined using the measured density data, while the surface excess energy and entropy were estimated using the measured surface tension data. The thermal gravimetric analysis showed that the thermal decomposition temperatures (T_onset) of [Emim][OMP] and [Emim][OMP] were 271.0℃ and 259.2℃, respectively. Differential scanning calorimetry results revealed that [Emim][OMP] and [Emim][OEP] had no melting or freezing points, but only glass-transition temperatures (T_g), and the T_g of [Emim][OMP] and [Emim][OEP] were -84.87℃ and -85.00℃, respectively. The Walden rule analysis demonstrated that [Emim][OMP] and [Emim][OEP] ionic liquids complied with the Walden rule well, and were classified as "good ionic liquids".

Key words: alkylimidazolium phosphonate ionic liquids, density, viscosity, conductivity, surface tension

摘要：

合成了1-乙基-3-甲基咪唑亚磷酸甲酯盐（[Emim][OMP]）和1-乙基-3-甲基咪唑亚磷酸乙酯盐（[Emim][OEP]）两种烷基咪唑亚磷酸酯离子液体，并使用核磁共振波谱仪和元素分析仪对产物进行了表征，在常压下测定了其热稳定性、相行为、密度和黏度（293.15~353.15K）、电导率和表面张力（293.15~343.15K）。采用自然对数方程关联离子液体的密度，根据实验值计算得到离子液体体积性质，包括热膨胀系数、分子体积、标准熵和晶格能。采用VFT方程关联离子液体黏度和电导率。采用线性方程关联表面张力，并根据实验值计算得到离子液体的表面熵和表面焓。实验结果表明，两种离子液体的分解温度（T_onset）分别为271.0℃和259.2℃，玻璃化温度（T_g）分别为 -84.87℃和 -85.00℃，离子液体的密度、黏度和表面张力随温度的升高而减小，而电导率随温度的升高而增大。Walden规则分析表明，两种烷基咪唑亚磷酸酯离子液体均符合Walden规则，且均被归类为“good ionic liquids”。

关键词: 烷基咪唑亚磷酸酯离子液体, 密度, 黏度, 电导率, 表面张力