Studies on Fluids and Fluid Mixtures: Connecting Theory with Experiment

流体和流体混合物的研究：理论与实验的结合

• 批准号: 0502196
• 负责人: Jane Lipson
• 金额: $ 27万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0502196&HistoricalAwards=false
• 关键词: Studies; Fluids; Fluid; Mixtures; Connecting

This grant is supported jointly by the Division of Materials Research and the Chemistry Division. The research is targeted at correlating microscopic structure and macroscopic behavior for fluids and their mixtures, with a particular emphasis on complex fluids. While the research tools are theoretical , the focus is on making connections with experiment and, where appropriate, simulation. An unusual opportunity afforded by this work is the ability to compare the results for the lattice and continuum models using the same theoretical approach. The behavior of complex fluids has been of high interest recently, stimulated by the increasingly sophisticated kinds of measurements accessible to scientists as well as the greatly expanded ability to simulate mixtures of dense fluids. The research proposed here builds upon the work of the PI and her group in using the Born-Green-Yvon (BGY) integral equation technique to model lattice and continuum fluids and mixtures. The lattice theory yields simple closed-form expressions for thermodynamic quantities. Advantages include its accessibility to non-theorists, and the ability to test it using lattice simulation results on complex systems. The continuum theory is capable of tackling more subtle issues involving the interplay between local structure and bulk properties. However, numerical methods are required and simulation data on mixtures are limited. The development of analogous lattice and continuum theories creates opportunities for determining which properties are sensitive to the imposition of a lattice constraint. The lattice studies proposed here focus on three projects: re-deriving the BGY theory to describe films and interfaces and studying the transition to the bulk; increasing the complexity of systems studied to include ternary mixtures; and mapping the thermodynamic results of the BGY theory onto the formalism of the Flory-Huggins chi parameter, the most widely-used characteristic parameter in the polymer community. This work will build on the demonstrated ability of the lattice BGY theory to describe simple and polymeric fluids and mixtures, and will exploit recently developed strategies for extracting much information from a minimal amount of experimental data. On the continuum side, the BGY theory has been used recently to study square-well fluids of up to 16-mers, and n-alkanes. These results will inform the proposed study of small branched alkanes, a project which will lead to a greater understanding of packing effects on fluid properties, and consequently of what may be lost when the lattice BGY theory is used. The second project focuses on square-well mixtures of short chain fluids; the components will range between monomers and 8-mers, thereby stretching the limit of current simulation results. This research will require consideration of the concentration dependence of the inter- and intramolecular distributions: how to treat it, and under what conditions it will become important. In this work connections between experimental data/analysis and the theoretical tools developed by the PI to study complex fluids will be expanded and strengthened. The outcome is that a more sophisticated combination of strategies, accessible to the materials community, will be available in solving problems relating to understanding connections between microscopic structure and macroscopic behavior. Local presentations by undergraduates and graduates will help them develop teaching skills. Results will also be disseminated through conference presentations by the PI and her research group at national meetings, and publications. The PI's efforts in research and teaching mentorship has resulted in an increase in the number of women in the ranks of graduate and postgraduate students and in faculty; it is expected that such effects will continue.

该补助金由材料研究部和化学部联合支持。 该研究旨在将流体及其混合物的微观结构和宏观行为相关联，特别强调复杂流体。 虽然研究工具是理论性的，但重点是与实验和适当的模拟相联系。这项工作提供的一个不寻常的机会是能够比较结果的晶格和连续模型使用相同的理论方法。复杂流体的行为最近引起了人们的高度兴趣，这是由于科学家可以获得越来越复杂的测量方法以及模拟稠密流体混合物的能力大大扩展。 这里提出的研究建立在PI和她的团队使用Born-Green-Yvon（BGY）积分方程技术来模拟晶格和连续介质流体和混合物的工作基础上。 格点理论给出了热力学量的简单的封闭式表达式。 其优点包括非理论家的可访问性，以及使用复杂系统上的晶格模拟结果对其进行测试的能力。 连续介质理论能够处理更微妙的问题，包括局部结构和整体性质之间的相互作用。 然而，数值方法是必需的，混合物的模拟数据是有限的。 类似的晶格和连续统理论的发展为确定哪些性质对晶格约束的施加敏感创造了机会。 这里提出的晶格研究集中在三个项目：重新推导的BGY理论来描述薄膜和界面，并研究过渡到散装;增加研究系统的复杂性，包括三元混合物;和映射的热力学结果的BGY理论的形式主义的Flory-Huggins chi参数，最广泛使用的特征参数在聚合物社区。 这项工作将建立在晶格BGY理论描述简单和聚合物流体和混合物的能力，并将利用最近开发的策略，从最少量的实验数据中提取大量的信息。 在连续介质方面，BGY理论最近已被用于研究高达16聚体的方阱流体和正构烷烃。这些结果将通知拟议的研究小支链烷烃，一个项目，这将导致更好地了解填充对流体性质的影响，从而可能会失去什么时，晶格BGY理论被使用。第二个项目的重点是短链流体的方井混合物;组分范围将在单体和8聚体之间，从而扩展了当前模拟结果的极限。 这项研究需要考虑分子间和分子内分布的浓度依赖性：如何处理它，以及在什么条件下它将变得重要。 在这项工作中， 数据/分析和理论 PI开发的用于研究复杂流体的工具将得到扩展和加强。其结果是，一个更复杂的策略组合，可访问的材料社区，将可用于解决与理解微观结构和宏观行为之间的联系有关的问题。本科生和研究生的本地演讲将帮助他们发展教学技能。 研究结果还将通过主要研究者及其研究小组在国家会议上的会议报告和出版物传播。 公共政策研究所在研究和教学指导方面的努力已经导致研究生和研究生以及教师队伍中妇女人数的增加;预计这种影响将继续下去。