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CAREER: Nonequilibrium Physics in Drying Soft Matter Solutions

职业：干燥软物质溶液中的非平衡物理

基本信息

批准号：
1944887
负责人：
Shengfeng Cheng
金额：
$ 51.48万
依托单位：
Virginia Polytechnic Institute and State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-06-01 至 2025-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1944887&HistoricalAwards=false
关键词：
CAREER Nonequilibrium Physics Drying Soft

项目摘要

NONTECHNICAL SUMMARYThis CAREER award supports computational and theoretical research, and education on the physics of evaporative drying of soft matter solutions. Paint is an example of soft matter solution. Paint is a particle suspension, which is a heterogeneous mixture of little particles suspended throughout the bulk of a solvent. A polymer solution is another example, which is a mixture of a solvent and polymers, long-chain molecules, dissolved in it. The drying process of these soft matter solutions provides a way to fabricate materials and a way to investigate physics in systems out of equilibrium. A famous illustration is the coffee ring effect, where a spill of coffee, a particle suspension like paint, leaves a ring-like deposit at its perimeter after drying. As another example, novel stratification phenomena have recently been discovered in suspension films containing particles of varied sizes, where the particles are found to form stratified layers according to their sizes after the suspensions are rapidly dried. The goal of the research is to use computer simulation techniques and simple physical models to elucidate the collective behavior of particles intrinsic to the evaporation processes of particle suspensions, polymer solutions, and their mixtures, and to map out the optimized drying conditions under which the resultant materials have desired structures. Such materials include multi-layered thin films of particles or polymer and composite materials with particulate fillers dispersed through a polymer matrix in a controlled manner. Specifically, this project aims to answer the following questions: How are the dissolved or dispersed components distributed in the dry film after a solution containing a mixture of solutes is dried quickly? How do particles and polymers migrate under concentration, temperature or other gradients that naturally emerge in a drying process? The findings will be used to guide the design of new solvent evaporation processes for more efficient material fabrication. The project integrates research into education and outreach activities that involve high school, undergraduate, and graduate students, high school and college educators, and the broader public. Specific goals include establishing a soft matter curriculum at Virginia Tech, cultivating students and future workforce with this curriculum, fostering the growth of a soft matter community in Virginia, and promoting the emerging concept of “material discovery accelerated through complementary efforts in computation, theory, and experiment” to the general public.TECHNICAL SUMMARYThis CAREER award supports computational and theoretical research, and education on the physics of evaporative drying of soft matter solutions. Solvent evaporation out of colloidal and polymer solutions and their mixtures is a tool frequently used to fabricate thin film materials, but our understanding of how the evaporation process of the solvent impacts the structures of the final colloidal and polymer films is largely based on experience and lacks predictive capabilities. The overarching objective of the research component is to use tools in nonequilibrium statistical mechanics to map out the optimized evaporation conditions under which the drying colloidal and polymer solutions yield materials with desired structures, including stratified colloidal thin films, layered polymer thin films, and polymer nanocomposites with controlled dispersion of nanoparticles. Adopting a hybrid computational/theoretical approach, the PI uses particle-based descriptions of liquids, colloidal particles, and polymers to probe the rich nonequilibrium, many-body physics intrinsic to evaporation processes. The main goal is to use molecular dynamics techniques to model the drying process of various soft matter solutions with an explicit solvent based on Lennard-Jones liquids or water in coarse-grained representations, and to reveal the effects of evaporation processes on the resulting material structures. These effects are challenging to evaluate with current experiments. Specifically, the PI aims to elucidate the physics of drying-induced stratification in various multicomponent soft matter solutions and the phoretic response of particles and polymers to concentration, temperature, chemical potential, and other gradients that emerge during the drying process. Studying solvent explicitly enables the PI to identify cases where an implicit solvent model might be appropriate, which can serve as a guidance for many other researchers who lack the resources to model a solvent explicitly for drying solutions. The project integrates research into education and outreach activities that involve students, educators, and the broader public and aim to establish a soft matter curriculum at Virginia Tech, to cultivate students and future workforce with this curriculum, to foster the growth of a soft matter community in Virginia, and to promote nonequilibrium physics and the emerging concepts of “computational thinking” and “materials via self-assembly” to the general public.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

本职业奖支持软物质溶液蒸发干燥的计算和理论研究，以及物理教育。油漆是软物质溶液的一个例子。油漆是一种颗粒悬浮液，它是悬浮在大部分溶剂中的小颗粒的非均匀混合物。聚合物溶液是另一个例子，它是溶剂和聚合物的混合物，长链分子溶解在其中。这些软物质溶液的干燥过程为制造材料和研究非平衡系统中的物理提供了一种方法。一个著名的例子是咖啡环效应，咖啡洒出来，像油漆一样的悬浮颗粒，干燥后在周围留下一个环状沉积物。作为另一个例子，最近在含有不同大小颗粒的悬浮膜中发现了新的分层现象，其中颗粒被发现在悬浮液迅速干燥后，根据其大小形成分层层。该研究的目标是利用计算机模拟技术和简单的物理模型来阐明颗粒悬浮液、聚合物溶液及其混合物蒸发过程中颗粒的集体行为，并绘制出优化的干燥条件，在此条件下所得材料具有所需的结构。这种材料包括颗粒或聚合物的多层薄膜，以及具有颗粒填料以受控方式分散通过聚合物基体的复合材料。具体来说，这个项目旨在回答以下问题：在含有溶质混合物的溶液快速干燥后，溶解或分散的成分是如何分布在干膜中的？颗粒和聚合物如何在浓度、温度或干燥过程中自然出现的其他梯度下迁移？研究结果将用于指导新的溶剂蒸发工艺的设计，以更有效地制造材料。该项目将研究整合到教育和推广活动中，涉及高中、本科生和研究生、高中和大学教育工作者以及更广泛的公众。具体目标包括在弗吉尼亚理工大学建立软物质课程，用这门课程培养学生和未来的劳动力，促进弗吉尼亚软物质社区的发展，并向公众推广“通过计算、理论和实验的互补努力加速物质发现”的新兴概念。本职业奖支持软物质溶液蒸发干燥的计算和理论研究，以及物理教育。胶体和聚合物溶液及其混合物的溶剂蒸发是制备薄膜材料的常用工具，但我们对溶剂蒸发过程如何影响最终胶体和聚合物薄膜结构的理解在很大程度上是基于经验的，缺乏预测能力。本研究的总体目标是利用非平衡统计力学中的工具来绘制最佳蒸发条件，在此条件下，干燥的胶体和聚合物溶液可以产生具有所需结构的材料，包括层状胶体薄膜、层状聚合物薄膜和具有可控分散的纳米颗粒的聚合物纳米复合材料。PI采用混合计算/理论方法，使用基于粒子的液体、胶体粒子和聚合物描述来探测蒸发过程中丰富的非平衡、多体物理特性。主要目标是利用分子动力学技术模拟各种软物质溶液与基于Lennard-Jones液体或水的明确溶剂在粗粒度表示下的干燥过程，并揭示蒸发过程对所得材料结构的影响。这些影响很难用目前的实验来评估。具体来说，PI旨在阐明在各种多组分软物质溶液中干燥诱导分层的物理原理，以及颗粒和聚合物对干燥过程中出现的浓度、温度、化学势和其他梯度的反应。明确地研究溶剂使PI能够确定隐式溶剂模型可能合适的情况，这可以作为许多其他研究人员的指导，他们缺乏资源来明确地为干燥溶液建模溶剂。该项目将研究整合到教育和推广活动中，涉及学生、教育工作者和更广泛的公众，旨在在弗吉尼亚理工大学建立软物质课程，培养学生和未来的劳动力，促进弗吉尼亚软物质社区的发展，并向公众推广非平衡物理和新兴概念“计算思维”和“通过自组装的材料”。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。