Modeling Nanoscale Confinement of Fluids: Applications to Fluids in Porous Materials and Liquids Wetting Nano-structured Surfaces

蒙森/0649552智力价值：该项目旨在对纳米尺度限制下的流体性质进行分子热力学建模。在此上下文中，限制一方面是指复杂多孔材料中的流体的情况，另一方面是指当液体与固体表面上的小尺度图案化接触时，其中限制由表面图案化的长度尺度产生。对于多孔材料中的流体，对基本热力学行为的理解对从催化到吸附分离到膜的应用以及在多孔材料表征中使用吸附具有重大影响。多孔的、结构化的或图案化的表面被液体的界面润湿已经在许多技术中引起相当大的兴趣，从防水纺织品的开发到气-液-固催化反应器的设计。最近，人们对纳米技术的应用也产生了兴趣，其中液体与固体接触，例如微米和纳米流体学、纳米光刻或“芯片上的实验室”技术。研究集中在两个领域：（i）开发和应用复杂孔隙结构中流体的粗粒度模型。研究人员正在开发一种统一的建模方法，以复杂的孔隙结构中的流体，可以在单个框架中处理润湿流体（气体吸附）和非润湿液体（汞孔隙率测定法）。该研究计划旨在了解这些系统的平衡状态以及滞后和伴随的动态。(ii)了解液体如何润湿拓扑和化学图案表面。研究人员使用密度泛函理论和分子模拟来计算图案化表面上液滴的密度分布。我们的目标是了解三相固-液-汽接触的细节，以及固体表面结构如何影响这一接触。这些研究领域基本上是由一个共同的主题流体约束和界面润湿现象。在这些领域的统计力学研究的一个中心问题是需要处理的三维密度分布在这些系统中的几何形状的复杂性。 这些模型应该允许一个桥梁的纳米和介观的长度尺度。本研究采用了平均场密度泛函理论和蒙特卡罗模拟等多种计算方法。更广泛的影响：该项目代表了分子热力学基础研究的一个例子，与重要的工程应用密切相关。该研究的主要影响是应用于多孔材料表征，使用气体吸附和压汞法。这项研究正在创建一个单一的分子建模框架，以理解这两种重要的表征技术。最近的研究表明，在纳米技术的重要性，了解界面在小的长度尺度。在这里开发的建模技术研究封闭的流体，重点是三维界面结构，可以在这方面也有显着的影响。该项目具有重要的教育组成部分，首先是通过研究生、博士后学者和本科生的参与。研究小组活动旨在培养学生交流研究成果的能力，我们的研究生参加本科课程的教学是他们学位课程的教育要求。在NSF支持下开发的材料将用于为本科生开发吸附热力学讲座，并为化学工程研究生的统计热力学课程开发项目材料。该项目的特点是与工业研究人员（Quantachrome公司）的合作，以及与莱比锡大学和柏林工业大学的研究小组的国际合作。

Monson / 0649552Intellectual merit: This project is directed at the molecular thermodynamic modeling of fluid properties under nano-scale confinement. In this context, confinement refers on the one hand to the case of fluids in complex porous materials and on the other to when a liquid is in contact with a small scale patterning on a solid surface, where confinement is created by the length scale of the surface patterning. For fluids in porous materials, understanding of fundamental thermodynamic behavior has significant impact on applications ranging from catalysis to adsorption separations to membranes, as well as in the use of adsorption for porous materials characterization. The interfacial wetting of porous, structured or patterned surfaces by liquids has been of considerable interest in many technologies, ranging from the development water resistant textiles to the design of gas-liquid-solid catalytic reactors. Recently, interest is also emerging in applications in nanotechnology where liquids contact solids such as micro- and nano-fluidics,nano-lithography or "lab on a chip" technologies.The research focuses on two areas: (i) Development and application of coarse-grained models for fluids confined in complex pore structures. The investigators are developing a unified modeling approach to fluids in complex pore structures that can treat both wetting fluids (gas adsorption) and non-wetting liquids (mercury porosimetry) in single framework. The research program seeks to understand the equilibrium states of these systems as well as hysteresis and the accompanying dynamics. (ii) Understanding how liquids wet topologically and chemically patterned surfaces. The investigators use density functional theory and molecular simulations to calculate the density distributions for liquid droplets on patterned surfaces. The goal is to understand the fine details of the three-phase solid-liquid-vapor contacting and how this is influenced by the structure of the solid surface. These research areas are linked fundamentally by a common theme of fluid confinement and interfacial wetting phenomena. A central issue for statistical mechanics research in these areas is the need to deal with the three-dimensionality of the density distribution in these systems created by the complexity in the geometry. These models should allow one to bridge the nanoscopic and mesoscopic length scales. This research features several computational methods including mean field density functional theory and Monte Carlo simulation. Broader Impacts: The project represents an example of fundamental research in molecular thermodynamics that is closely linked with important engineering applications. The primary impact of the research is in application to porous material characterization using gas adsorption and mercury porosimetry. The research is creating a single molecular modeling framework for understanding both of these important characterization techniques. Recent research in nanotechnology has shown the importance of understanding interfaces at small length scales. The modeling techniques developed here for studying confined fluids, which focus on three-dimensional interfacial structure, can make a significant impact in this area also. The project has significant educational components, in the first instance through the involvement of graduate students, postdoctoral scholars and undergraduates. Research group activities are designed to develop the ability of students to communicate their research achievements, and our graduate students participate in teaching undergraduate courses as an educational requirement of their degree program. Material developed under NSF support will be used to develop lectures in adsorption thermodynamics for undergraduates and project materials for a course in statistical thermodynamics for chemical engineering graduate students. The project features collaboration with researchers in industry (Quantachrome Corporation) as well as international collaboration with research groups at the University of Leipzig and the Technical University of Berlin.