UNS: Predicting the Interfacial Activity of Complex Grafted Nanoparticles

UNS：预测复杂接枝纳米粒子的界面活性

• 批准号: 1510635
• 负责人: Robert Riggleman
• 金额: $ 33.72万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1510635&HistoricalAwards=false
• 关键词: UNS; Predicting; Interfacial; Activity; Complex

#1510635Riggleman, Robert A. Numerous consumer products ranging from cosmetics, detergents, and fluids for oil recovery require the stabilization of two immiscible fluids (e.g., oils and water) as an emulsion, where one phase (typically the oil) is dispersed as stable droplets in the second phase (water). Recently, experiments have shown that adding nanometer-sized particles that have polymer chains grafted to their surface is an unusually effective and inexpensive method for stabilizing these emulsions, but the mechanism for stabilization remains poorly understood. The research goal of this proposal is to study the effect of the chemistry of the grafted polymer chains on the interfacial properties of grafted nanoparticles. We will study the conformations of the polymer brush on isolated nanoparticles, the interactions of multiple nanoparticles, including their effect on the interfacial tension and self-assembly at the interface, and we will study the effect of having charges on the grafted polymer chains. These calculations are enabled by recent simulation techniques developed in our group. Our educational goals include the training of graduate students in polymer science and engineering, and state-of-the-art simulation techniques. We will continue our group's effort at involving undergraduate and high school students in our research. Finally, we will impact the broader scientific community by developing and publishing simulation codes that perform our calculations.In recent years, there has been a growing interest in the thermodynamics of nanoparticles functionalized with polymers for use in applications such as separations membranes and oil extraction fluids. By carefully tuning the interactions between the particle cores, the grafted chains, and any components that make up the host matrix of the grafted particles, one can easily control optical and mechanical properties simply by controlling the aggregation and dispersion state of the polymer. Very recently, experiments have shown that grafted nanoparticles exhibit a remarkable interfacial activity in oil and water emulsions, and they are highly effective at stabilizing the emulsions over long periods of time at surprisingly low concentrations. Furthermore, the effect of the grafting architecture has not been explored at all; recent advances in synthetic chemistry enables grafting diblock polymers, a mixture of homopolymers, or patchy (Janus) grafting on the surface of nanoparticles. This large parameter space available to experimentalists creates a need for molecular modeling that can guide experiments toward systems that show the most promise for various applications. The goal of this proposal is to use a field theoretic simulations framework recently developed by my group to examine the structure and interfacial properties of complex grafted nanoparticles. We will examine mixed brushes, diblock polymer brushes, and Janus brushes on the surface of nanoparticles as a function of the particle core size, grafting density, brush composition, and interactions with the matrix phases. Finally, we will examine how the picture changes when one of the polymers carries a charge, while incorporating the effects of ion solvation and dielectric mismatch between the two phases creating the interface. Overall, we expect our results to have a significant impact on the design of future experiments. Our efforts will have a broad impact to society by providing fundamental insights into the design of fluids for oil extraction and a wide variety of consumer products. In addition to the doctoral students trained in polymer physics and state-of-the-art molecular modeling techniques, our work has a substantial education and outreach component involving undergraduate (and potentially high school student) research, course development, and outreach to the scientific community in general. Our lab has one undergraduate student currently working with us who has co-authored a paper, and in the summer of 2014 we had a local high school student visit our lab, performing molecular dynamics simulations of polymer melts. We are developing course modules both for specialized molecular modeling courses as well as broad first-year statistical mechanics courses that introduce and develop the field theoretic simulations framework. Finally, in addition to the standard conference meetings promoting our work, we are developing a code base that we can publish and freely release to the public. Our hope is to broaden the application and use of the field theoretic simulations framework, and we believe this can be most effectively achieved by lowering the barrier to entry. Making our codes widely available is a key part of that vision.

#1510635Riggleman, Robert A. 化妆品、清洁剂和采油流体等众多消费品需要将两种不混溶的流体（例如油和水）稳定为乳液，其中一相（通常是油）分散为稳定状态第二相（水）中的液滴。最近，实验表明，添加表面接枝有聚合物链的纳米颗粒是稳定这些乳液的一种异常有效且廉价的方法，但其稳定机制仍知之甚少。本提案的研究目标是研究接枝聚合物链的化学性质对接枝纳米颗粒界面性能的影响。我们将研究孤立纳米颗粒上聚合物刷的构象、多个纳米颗粒的相互作用，包括它们对界面张力和界面自组装的影响，并且我们将研究带电荷对接枝聚合物链的影响。这些计算是通过我们小组最近开发的模拟技术实现的。我们的教育目标包括培养聚合物科学与工程以及最先进的模拟技术方面的研究生。我们小组将继续努力让本科生和高中生参与我们的研究。最后，我们将通过开发和发布执行我们计算的模拟代码来影响更广泛的科学界。近年来，人们对用聚合物功能化的纳米粒子的热力学越来越感兴趣，这些纳米粒子用于分离膜和石油开采流体等应用。通过仔细调节颗粒核、接枝链以及构成接枝颗粒主体基质的任何组分之间的相互作用，只需控制聚合物的聚集和分散状态，就可以轻松控制光学和机械性能。最近，实验表明，接枝纳米颗粒在油水乳液中表现出显着的界面活性，并且它们在令人惊讶的低浓度下长时间稳定乳液非常有效。此外，嫁接结构的效果还没有被探索过。合成化学的最新进展使得能够在纳米颗粒表面接枝二嵌段聚合物、均聚物混合物或斑片（Janus）接枝。实验人员可用的大参数空间产生了对分子建模的需求，分子建模可以指导实验走向最适合各种应用的系统。该提案的目标是使用我的团队最近开发的场论模拟框架来检查复杂接枝纳米颗粒的结构和界面特性。我们将检查纳米颗粒表面上的混合刷、二嵌段聚合物刷和 Janus 刷，作为颗粒核心尺寸、接枝密度、刷组成以及与基质相相互作用的函数。最后，我们将研究当其中一种聚合物带有电荷时图像如何变化，同时结合离子溶剂化和形成界面的两相之间的介电失配的影响。总的来说，我们预计我们的结果将对未来实验的设计产生重大影响。我们的努力将为石油开采和各种消费品的流体设计提供基本见解，从而对社会产生广泛的影响。除了接受过聚合物物理学和最先进的分子建模技术培训的博士生之外，我们的工作还有大量的教育和推广工作，涉及本科生（以及潜在的高中生）研究、课程开发和科学推广。一般社区。我们的实验室目前有一名本科生与我们一起工作，他共同撰写了一篇论文，2014 年夏天，我们有一名当地高中生参观了我们的实验室，对聚合物熔体进行分子动力学模拟。我们正在为专门的分子建模课程以及广泛的一年级统计力学课程开发课程模块，以介绍和开发场论模拟框架。最后，除了促进我们工作的标准会议之外，我们正在开发一个可以发布并免费向公众发布的代码库。我们的希望是扩大场论模拟框架的应用和使用，我们相信通过降低进入门槛可以最有效地实现这一目标。使我们的代码广泛可用是这一愿景的关键部分。