新型低共熔溶剂的制备、表征及物性研究

Synthesis,Characterizations and Their Physical Properties of Novel Deep Eutectic Solvents

以氯化1-丁基-3-甲基咪唑鎓([Bmim]Cl)和二元羧酸为原料,由不同摩尔比混合制备了一类新型低共熔溶剂,采用红外光谱对[Bmim]Cl和二元羧酸之间的作用进行了分析。分别测定了其粘度、电导率、密度、折射率等物理性质,并研究了温度、二元羧酸结构和摩尔比对这些物理性质的影响。结果表明,新型低共熔溶剂的粘度随温度的升高而降低,电导率随温度的升高而增加。温度对两者的影响可以采用VTF方程进行精确地拟合。新型低共熔溶剂的密度随温度的升高而呈线性下降。对新型低共熔溶剂的过量摩尔体积进行计算的结果表明,过量摩尔体积均为正值,二元羧酸对过量摩尔体积的贡献远大于[BMIM]Cl,而结构特性的贡献多于物理作用。折射率和密度随二元羧酸碳数的变化趋势基本相似。

Novel deep eutectic solvents( DES) were prepared using 1-butyl-3-methylimidazolium chloride( [Bmim]Cl) and dicarboxylic acids( malonic acid,succinic acid,glutaric acid or adipic acid) at different molar ratios( 1∶ 0. 5 or 1 ∶ 1). All as-prepared DES are colorless transparent liquid at room temperature. Their physical properties such as viscosity, conductivity, density and refractive index were determined. The influence of temperature,carbon number of dicarboxylic acids and molar ratio of dicarboxylic acids in DES system on their physical properties was investigated. The results showed that their viscosity decreased rapidly and the conductivity increased with increase of temperature. The carbon number of dicarboxylic acids showed different influence on the viscosity and conductivity according to molar ratio,with odd-even effect and packing effect being the main factor. The temperature dependence of viscosity and conductivity was investigated through systemically quantitative analysis using Arrhenius equation and VTF equation. The activation energy of viscous flow( E,48 ~ 84 k J/mol) and activation energy of the ionic conductivity( Eσ,37 ~ 73 k J/mol) were calculated by Arrhenius plots. In the temperature range of 298. 15 ~ 333. 15 K,the temperature dependence of viscosity and conductivity both showed a well accordance with VTF models( all R > 0. 9999) than Arrhenius models. The densities of DES also decreased linearly with increase of temperature. Excess molar volumes( VE) of DESs were all positive. The contribution of dicarboxylic acids on VEis more than that of [Bmim]Cl. The refractive index of DES( at 298. 15K) decreased with increase of molar ratio of dicarboxylic acids in DES system and showed a similar trend to densities with increase of carbon number in dicarboxylic acids.