热可逆离子液体-低共熔溶剂双水相体系的相行为及理化特性研究

与聚合物双水相体系相比，离子液体双水相体系具有相分离效率高和选择性强的特点，在萃取领域得到了广泛关注。然而，离子液体双水相体系中常见的kosmotropic组分为无机盐或有机盐，溶液环境通常呈现强碱性，不利于保持萃取分子的稳定性和生物活性。以低共熔溶剂替代盐类作为kosmotropic组分、以离子液体为chaotropic组分构建新型离子液体-低共熔溶剂双水相体系，考察了不同温度下的相行为规律，筛选出具有高临界共熔温度（UCST）和低临界共熔温度（LCST）两种截然相反的热可逆相转变行为的萃取体系，从宏观角度探索了离子液体-低共熔溶剂-水三元体系的黏度、密度、电导率以及pH等理化特性随温度变化的规律，利用量子化学计算从微观角度分析离子液体、低共熔溶剂与水分子之间的相互作用。研究旨在揭示热可逆离子液体-低共熔溶剂双水相体系的成相机理，为萃取温敏性生物分子设计新的理想萃取体系提供基础数据。

Phase behavior and physicochemical properties of thermoreversible aqueous biphasic systems composed of ionic liquids and deep eutectic solvents

Compared with the polymer-based aqueous biphasic systems (ABSs), the ionic liquid (IL)-based ABSs exhibited higher phase separation efficiency and stronger selectivity, and have attracted increasing attention in separation and purification. However, the kosmotropic components in the IL-based ABSs were inorganic salts or organic salts, which were adverse to maintain the stability and biological activity of the biomolecules in a strong alkaline solution. In this study, deep eutectic solvents (DESs) were used as alternative kosmotropic components to form novel ABSs with ILs (chaotropic components). The law of phase behavior at different temperature was investigated to screen out thermoreversible systems showing upper critical solution temperature (UCST) and lower critical solution temperature (LCST). Moreover, the physicochemical properties, such as the viscosity, density, conductivity, and pH of the IL-DES-water ternary systems as function of temperature were explored. Furthermore, quantum chemical calculations were used to analyze the interaction between the IL and water or DES and water. The research aims to reveal the mechanism of the thermoreversible IL-DES ABS and provide essential data for the desigin of a new ideal extraction system for the extraction of thermo-sensitive biomolecules.