【摘要】 采用近红外光谱技术研究了含水量（摩尔分数）在5%～95%范围内水结构对低共熔溶剂(DESs)的氢键网络结构的影响.通过分析氯化胆碱与尿素混合后不同时间的近红外光谱,发现了尿素—NH基团与氯化胆碱Cl~-相互作用的光谱信息,表明DESs熔点降低的原因主要是NH···Cl~-氢键的形成.通过分析不同含水量的DESs-水混合物的近红外光谱,发现了水分子之间以及水分子与尿素中—NH和C=O基团相互作用的光谱信息,表明水在DESs中主要以3种结构存在:类大体积水、与尿素C=O键合的水以及—NH分子间的桥连水.类大体积水破坏DESs中NH···Cl~-,使体系的稳定性降低,而尿素—NH分子间的桥连水和与C=O键合的水使体系的稳定性增加.DESs中3种水结构的相对比例与含水量有关,含水量在40%～80%既能有效降低体系的黏度,又能维持DESs的性质.更多还原

【Abstract】 The hydrogen bond network structure of choline chloride/urea deep eutectic solvents(DESs)-water mixtures was studied in the range of 5%—95%water content by near infrared spectroscopy.Through the analysis of the near-infrared spectra after choline chloride and urea mixing,the spectral feature of the interaction between urea—NH group and choline chloride Cl~-was found,indicating that the formation of NH···Cl~-was the reason for the decrease of DESs melting point.Through the near-infrared spectrum analysis of DESs-water mixtures with different water contents,the spectral information of the interaction between water molecules and between water molecules and the—NH and C=O groups in urea was found.Water mainly exists in three kinds of structures,including the bulk water,the hydrated water with urea C=O and the bridge water connect—NH groups.The bulk water destroyed NH···Cl~-in DESs,reducing the stability of the system,while the bridge water between urea—NH molecules and the hydrated water with urea C=O increase the stability of the system.The relative content of the three water structures in DESs is related to the water content.The water content of 40%—80%can not only effectively reduce the viscosity of the system,but also maintain the properties of DESs.更多还原