Adsorption in Confined Films

受限薄膜中的吸附

基本信息

批准号：
1902364
负责人：
William Ducker
金额：
$ 38.66万
依托单位：
Virginia Polytechnic Institute and State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-07-01 至 2022-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1902364&HistoricalAwards=false
关键词：
Adsorption Confined Films

项目摘要

Many commonplace products are composed of collections of particles suspended in liquid. Examples include paints, food products and cosmetics. An important feature of these products is that the particles remain in particular arrangements, rather than aggregating or separating from the suspending liquid. Maintaining the proper arrangement of the particles can be challenging, especially for products with long shelf lives. The key aspect of maintaining the desired arrangement of particles is to control what happens in the small gaps where the particles almost touch each other. This project takes advantage of a recent development in our ability to make well-defined examples of these small gaps. The project examines how molecules adsorb into the gaps, and how the adsorption is affected by the gap size. This molecular adsorption is critical to controlling whether the gaps close or widen with time, and thus whether consumer products maintain the most useful arrangement. The research in this project will be integrated into programs that teach undergraduate and graduate students, and will provide educational tools to inspire high school students, especially those underrepresented in STEM fields, to continue in science and engineering studies.Adsorption of ions, surfactants, polymers, and particles is a key factor in determining the stability of colloidal dispersions in thin wetting films, and thus is central to many engineering processes. Adsorption at single interfaces has been well studied, but the directly relevant quantity for colloid stabilization is adsorption in a thin film between two interfaces. This has only rarely been measured in prior work. A new technique has been developed to measure the amount of a species in nanometer-scale films between two solids. This technique will be used to measure adsorption in critical regimes where simple modeling based on Poisson-Boltzmann theory is expected to fail, such as in concentrated solutions, multivalent ions, surfactants, and particles. The technique has three elements: (1) fabrication of a robust thin film between two solids with a continuous gradient of thicknesses in the range of 1?200 nm; (2) measurement of film thickness by interferometry; and (3) measurement of the amount of adsorbed molecules from the intensity of fluorescence emission. The expected outcomes are: (1) accurate measurements of amounts of species in thin films; (2) assessment of the validity of common models; (3) insight into the stabilization of films in various applications; and (4) some development of the method to measure the profile of fluorophore concentration in the direction normal to a planar film. We will integrate this work into the "Computers and Technology at Virginia Tech" (C-Tech2), which is an annual two-week summer program for 120 female high school to participate in hands-on activities to help develop and sustain interest in science and engineering. The work will also provide interdisciplinary training for a graduate student in the fields of optics, microfabrication, modelling, and microscopy. Undergraduates will work on the project, with the aim of inspiring them to pursue graduate study in engineering or science.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.

许多常见的产品由悬浮在液体中的颗粒集合组成。例子包括油漆，食品和化妆品。这些产品的一个重要特征是颗粒保持在特定的布置中，而不是汇总或与悬浮液体分离。保持颗粒的适当布置可能具有挑战性，尤其是对于具有长寿寿命的产品。保持颗粒所需排列的关键方面是控制粒子几乎彼此接触的小间隙中发生的事情。该项目利用了我们最近制作这些小空白示例的能力的最新发展。该项目检查了分子如何吸附到差距中，以及吸附如何受间隙大小的影响。这种分子的吸附对于控制差距是随着时间的关闭还是扩大的，因此消费产品是否保持最有用的布置至关重要。该项目中的研究将集成到教授本科生和研究生的课程中，并将提供教育工具，以激发高中生，尤其是那些在STEM领域中的人数不足的学生，以继续从事科学和工程研究。对离子，表面活性剂，聚合物和颗粒的吸附是确定胶体分散剂的稳定性，从而确定薄膜的稳定性。对单个接口处的吸附进行了充分的研究，但是胶体稳定的直接相关量是在两个接口之间的薄膜中吸附。这只是在先前的工作中很少衡量。已经开发了一种新技术来测量两种固体之间的纳米尺度膜中的物种量。该技术将用于测量关键方案中的吸附，其中预计基于Poisson-Boltzmann理论的简单建模将失败，例如在集中溶液，多价离子，表面活性剂和颗粒中。该技术具有三个元素：（1）在两个固体之间制造稳健的薄膜，其厚度连续梯度在1？200 nm范围内；（2）通过干涉测量法测量膜厚度；（3）测量荧光发射强度的吸附分子量。预期的结果是：（1）薄膜中物种量的准确测量；（2）评估常见模型的有效性；（3）深入了解膜在各种应用中的稳定；（4）方法的一些发展，用于测量荧光团浓度在与平面膜正常的方向上的特征。我们将将这项工作集成到“弗吉尼亚理工学院的计算机和技术”（C-TECH2）中，这是一年一度的为期两周的夏季计划，针对120位女高中，以帮助发展和维持对科学和工程的兴趣。这项工作还将为光学，微分化，建模和显微镜领域的研究生提供跨学科培训。本科生将在该项目上工作，目的是激发他们从事工程或科学领域的研究生学习。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估审查标准来评估的。