基于流体-固体表面粗粒化模型的负载离子液体吸收CO2分子模拟研究

Ionic liquids (ILs) have been applied to the IL immobilization into porous solid supports and supported ionic liquid membranes to absorb CO2, and the macroscopic law is not applicable to the liquid film with nano-scale thickness. For ILs-surface/interface system, both the structure and the time scale are in the mesoscopic, coarse grained simulation can be used to obtain the nano/micro scale properties. In this project surface force information is obtained using atomic force microscopy (AFM), and then the ILS-surface coarse-grained model which is closely related to the surface of material is established. It is used to simulate the CO2 absorption of IL immobilization by coarse grained simulation. The results can be used to explain the absorption capacity and the mechanism of the changes of the transfer nature of confined ILs, and provide quantitative data and guidance for the design of IL immobilization absorbing CO2 material which cannot be from macro theory in nanometer scale. Through the establishment of ILs-surface coarse-grained force field, AFM test, coarse grain simulation and IL immobilization absorbing CO2 experiments are combined in one. The real surface information taking by AFM test is reflect to simulation, the characteristic scale in which the experimental phenomenon occurred is figured out to realize the coincidence of simulation and experiment in the field of micro-scale. Using AFM to establish the coarse grained model has not yet been found in the existing literature. The characteristics of the force field are: coarse graining the surface structure+ refining the force of the surface. It is an innovative modeling idea of coarse grain simulation.

离子液体（ILs）已被应用于负载离子液体及支撑离子液膜吸收CO2，宏观规律对纳米尺度液膜厚度已不适用。对于结构和时间尺度均处于介观的ILs表界面体系，粗粒化模拟能得到纳微尺度性质。本项目利用原子力显微镜（AFM）得到表面力信息，建立与材料表面密切相关的ILs-表面粗粒化模型，用于负载ILs吸收CO2的粗粒化模拟，从微观上解释受限ILs吸收容量和传递性质变化的机理，为负载ILs吸收CO2材料设计提供宏观理论不能得到的纳米尺度定量数据和设计指导。本项目通过ILs-表面粗粒化力场的建立，集AFM测试，粗粒化模拟和负载ILs吸收CO2实验于一体，将AFM测试得到的真实表面信息反映到模拟之中，抓住实验现象产生的特征尺度，实现模拟和实验在微观领域的尺度重合。利用AFM来建立粗粒化模型，在已有的文献中尚未发现，该力场的特点是：表面结构的粗化+表面力的精确化，是粗粒化模拟的一种创新建模思想。

离子液体被认为是最具潜力的捕集CO2新材料之一。为提高离子液体传质速度和吸收面积，负载离子液体吸收剂被广泛应用，但纳米担载的表面效应机制机理还不清楚。项目利用AFM从介观尺度的界面作用力探测出发，研究了离子液体在不同材料，不同粗糙度表面的纳米润滑与摩擦行为及其与载荷的关系，探索了离子液体与固体表面的相互作用。AFM测试与粗粒化分子模拟结合，研究固体材料性质和表面性质对其在表面润湿行为的影响，对受限离子液体的结构和光谱性质进行了模拟。进行了离子液体负载受限体系吸收CO2性质及相关传递性质等的实验和模拟，将CO2的吸收与不同固载量的离子液体膜表面纳米摩擦系数进行关联。此外还针对离子液体与界面相互作用，采用分子动力学模拟研究离子液体双电层性质。本项目的研究从AFM测试，到粗粒化力场建立，以及模拟、实验结果的相互验证均进行了深入的探讨。从微观上解释了受限条件下CO2吸收容量和传递性质变化背后的机制机理，为负载离子液体吸收CO2的材料设计提供了理论依据。