醚基功能化离子液体[MOEMIm]Cl和[EOEMIm]Cl热力学性质

通过核磁共振氢谱,核磁共振碳谱,元素分析和热重分析对醚基功能化的离子液体MOEMIm]Cl和EOEMIm]Cl进行了表征。在温度范围T=288.15–328.15 K内,测定了离子液体MOEMIm]Cl和EOEMIm]Cl的密度(ρ)、表面张力(γ)和折光率(nD)。根据这些实验数据,讨论并计算了离子液体MOEMIm]Cl和EOEMIm]Cl的体积性质。计算出离子液体MOEMIm]Cl和EOEMIm]Cl的摩尔表面吉布斯自由能(gs)、摩尔表面熵(s)、摩尔表面焓(h)、摩尔极化度(Rm)和摩尔极化率(αp),h均近似为一个常数说明这两种离子液体从内部到表面的过程是一个等库仑过程,同时这两种离子液体的Rm和αp均与温度无关。本文还用摩尔表面Gibbs自由能改进Lorentz-Lorenz方程并预测离子液体表面张力,预测值与实验值高度相关。

Thermodynamic Properties of the Ether-Based Functionalized Ionic Liquids [MOEMIm]Cl and [EOEMIm]Cl

Functionalized ionic liquids containing ether groups can be obtained through reasonable design. The unique properties of ether-based functionalized ionic liquids are attractive for a variety of practical applications. To further develop these ether-based functionalized ionic liquids, it is important to accurately describe the thermophysical properties of ether-based functionalized ionic liquids and to predict, simulate, and optimize theoretical models of thermophysical properties. Herein, the ether-functionalized ionic liquids MOEMIm]Cl and EOEMIm]Cl were characterized by nuclear magnetic resonance spectroscopy, elemental analysis, and thermogravimetric analysis. The density (ρ), surface tension (γ), and refractive index (n_D) of MOEMIm]Cl and EOEMIm]Cl were measured at 5 K intervals between 288.15 and 328.15 K. Based on the obtained experimental data, the molar volume (V), molecular volume (V_m), standard entropy (S₍₂₉₈₎⁰), and lattice energy (U_POT) of MOEMIm]Cl and EOEMIm]Cl were calculated and the data obtained at 298.15 K were compared. The comparison results agreed well with the literature values within the experimental error range and indicated that both MOEMIm]Cl and EOEMIm]Cl exhibit small lattice energies and are in the molten state at room temperature (T = 298.15 K). Based on these experimental data, the molar surface Gibbs free energy (g_s), molar surface entropy (s), molar surface enthalpy (h), molar polarization (R_m), and molar polarizability (α_p) of MOEMIm]Cl and EOEMIm]Cl were also calculated. The calculation results show that the molar surface enthalpy (h) is approximately constant, that is, the molar surface constant pressure heat capacity is close to zero, indicating that the process of heat capacity change from the inside to the surface of the ionic liquid is an equivalent coulomb process. Simultaneously, the calculation results showed that the molar polarization (R_m) and molar polarizability (α_p) of the ionic liquids were independent of temperature, indicating that R_m and α_p reflect the induced dipole effect of the ionic liquid. The molar surface Gibbs free energy definition equation was combined with the Lorentz-Lorenz equation to obtain a novel modified Lorentz-Lorenz equation and was used to predict the surface tension of the MOEMIm]Cl and EOEMIm]Cl liquids. The values predicted using this combined equation were highly correlated with the experimental values.