超高压条件下室温离子液体凝聚态结构和性质研究

Room temperature ionic liquid, which is viewed as a kind of super green solvent, has broad application prospect in industrial production, and it is of great significance to study its condensed structures and properties. In this project, the condensed structures, crystallization processes and properties of room temperature ionic liquids(such as [CnMIM][PF6] and [CnMIM][BF4]) will be researched under high pressure, low temperature and other extreme conditions by in situ small angle and wide-angle X-ray scattering, in situ Raman, infrared and fluorescence spectroscopy, in situ differential thermal analysis and atomic force microscope. The details will be discussed as follows: to study the thermodynamic stability and transformative process of ionic liquids with different crystal structures under high pressure or other extreme conditions, and to explore the role of the metastable state in the ordering process of room temperature ionic liquids, and to analyze the effect of pressure and temperature on the crystallization of ionic liquids. At the same time, the glassy structure and molecular dynamics of room temperature ionic liquids will be studied by Extended X-ray absorption fine structure, static and dynamic light scattering. And then we could obtain the condensed structures, crystallization processes and properties of room temperature ionic liquids and explore the intrinsic relationship between the condensed structure and properties of room temperature ionic liquids under ultra-high pressure conditions. Furthermore, the mechanism of crystallization of the room temperature ionic liquid will be elucidated in details, which will provide a new idea for the recovery and purification of room temperature ionic liquids.

室温离子液体作为一种超级绿色溶剂，在工业化生产中具有广阔的应用前景，其凝聚态结构和性质研究具有非常重要的意义。本项目拟利用原位小角和广角X射线散射，原位拉曼、红外和荧光光谱，原位差热分析以及原子力显微镜等研究室温离子液体（如[CnMIM][PF6]和[CnMIM][BF4]等体系）在高压、低温等极端条件下的凝聚态结构、结晶过程和性质等。内容包括：研究高压等极端条件下室温离子液体不同晶型的热力学稳定性和相互转变过程；探索亚稳态在室温离子液体有序化过程中的作用；分析压力、温度等对离子液体结晶的影响；同时，利用扩展X光吸收精细结构，静态和动态光散射研究室温离子液体在液态和玻璃态的结构，获取高压等极端条件下室温离子液体的凝聚态结构和性质等信息, 探讨室温离子液体超高压条件下结构和性质之间的内在联系，阐明室温离子液体结晶固化机制，为室温离子液体的回收和提纯提供新的思路。

本项目利用原位光谱技术，系统地研究了室温离子液体在超高压等极端条件下的凝聚态结构和性质等，探讨了室温离子液体超高压条件下结构和性质之间的内在联系，分析了室温离子液体结晶固化机制。首先，研究了离子液体在高压等极端条件下的结晶过程及凝聚态结构，获取了[Bmim][PF6]和[C10MIM][BF4]从熔融态结晶固化的相变点，并对高压相的结构和构象进行了深入的分析；发现了[OMIM][PF6]从过压的玻璃态泄压诱导结晶现象，这也提供了除直接加压诱导结晶外另一种实现离子液体结晶的方法；用高压的方法诱导[Emim][PF6]从甲醇溶液中结晶，探讨了离子液体从溶液中结晶固化机制，为离子液体的回收和提纯提供新的方案；研究了不同加压速度对 [Emim][CF3SO3]结晶固化的影响，其压致相变的动力学效应与加压速度密切相关，这表明加压速度在离子液体的高压相变研究中是一个不可忽视的因素。其次，研究了离子液体在高压下的玻璃化，探索离子液体作为传压介质的潜在用途，获取[EMIM][EtOSO3]、[BMIM][TFSI]、[HMIM][PF6]、[HMIM][BF4]和[BMIM][BF4]在高压下的玻璃化转变压力点，分析了离子液体高压下玻璃化转变的结构变化，并且对[BMIM][BF4]压腔中的压力梯度进行了定量测量，分析了压腔中的静水压性，探索离子液体作为传压介质的潜在用途。再次，获取高压下离子液体的宏观性质，如溶解度、粘度等，探讨了宏观性质和微观结构的相关性，创新性地定量测量了高压下 [Emim][PF6]在甲醇溶液中的的溶解度；利用自制高压粘度测量实验装置，获取了GPa范围内[EMIM][BF4]、[BMIM][BF4]和[HMIM][BF4]的粘度数据，极大地拓展了目前文献中离子液体高压粘度测量压力范围。综上所述，本项目通过研究超高压等极端条件下有关离子液体凝聚态结构和性质，深化了对离子液体特殊性能机理的认识，促进了高压下离子液体的基础研究和应用，也为离子液体的结晶固化提供了新的思路。