Active Surface Agents: Enhanced Transport by Active Colloids at Fluid Interfaces

活性表面剂：活性胶体在流体界面处增强传输

• 批准号: 1943394
• 负责人: Kathleen Stebe
• 金额: $ 36.57万
• 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: 2020
• 资助国家: 美国
• 起止时间: 2020-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1943394&HistoricalAwards=false
• 关键词: Active; Surface; Agents; Enhanced; Transport

Active colloids are micron-scale self-propelled objects. They accumulate near interfaces, bringing as yet largely untapped degrees of freedom to interfacial engineering. Here, active colloid motion will be studied to develop these objects as Active Surface Agents. These agents can improve mixing for chemical processes, and can lead to new encapsulation and release methods. Furthermore, they are important in new technological spaces like micro-robotics, where small objects perform tasks like moving cargo or releasing a signal. The field of active colloids is inspired by motile bacteria, which can move at extraordinary rates, typically over distances ten times greater than their size in a second. There are also synthetic active colloids. An important example is a polymer micron bead with a platinum patch which reacts with common chemicals like hydrogen peroxide, which fuels their motion. Plain colloids, absent activity, are used to form organized structures at fluid interfaces between fluids that do not mix to stabilize oil in water emulsions, widely used to encapsulate oily substances in water in personal care products and to formulate pharmaceuticals. Fluid interfaces are special environments for chemical reaction and separation. For example, if catalysts are present at fluid interfaces, reagents in the oil phase can form products that prefer the water phase. This facilitates reaction and separation in green processes. Innovation can have economic and social impact. Furthermore, this research will advance Sciences Technology Engineering and Mathematics education, including doctoral student and undergraduate researcher training, and as course material in the Interfacial Phenomena course. The outcome of the proposed research will be presented in outreach activities to attract students from diverse backgrounds to engineering. Furthermore, research findings will be conveyed in demonstrations for the public.Bacteria will be used as a model system. This research will develop a general framework to identify desired active surface agent properties including trajectory type, propulsion strength, and surface density to generate a desired active interfacial layer. The results will lay the ground work to promote mixing at interfaces of emulsions or of thin liquid films or other multi-phase system using active colloidal layers. All active colloids obey similar hydrodynamic descriptions, which this research will develop. Active colloids accumulate near interfaces and can swim adjacent to them, trapped via hydrodynamic interactions, or can swim in an adhered state with complex trajectories that differ from those in bulk in both form and spatio-temporal implications. This research will develop a library of responses of individual swimmers on and near interfaces to understand their individual behaviors using experiment and theory. This research will probe how motion in the interface, a two dimensional active sheet, propagates into the adjacent fluids. By understanding these implications, new design rules for active interfaces can be established to enhance transport in multiphase systems.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.

活性胶体是微米级的自推进物体。它们在界面附近积累，为界面工程带来了很大程度上尚未开发的自由度。本文将研究活性胶体的运动，以开发这些物体作为活性表面剂。这些试剂可以改善化学过程的混合，并可以导致新的封装和释放方法。此外，它们在微型机器人等新技术领域也很重要，在微型机器人中，小物体可以执行移动货物或释放信号等任务。活性胶体领域的灵感来自于能动的细菌，它们可以以非凡的速度移动，通常在一秒钟内移动的距离是它们大小的十倍。也有合成的活性胶体。一个重要的例子是一个带有铂片的聚合物微米珠，它与过氧化氢等常见化学物质反应，为它们的运动提供燃料。 无活性的普通胶体用于在不混合的流体之间的流体界面处形成有组织的结构以稳定水包油乳液，广泛用于在个人护理产品中将油性物质包封在水中以及配制药物。流体界面是化学反应和分离的特殊环境。例如，如果催化剂存在于流体界面处，则油相中的试剂可以形成优选水相的产物。这有利于绿色工艺中的反应和分离。创新可以产生经济和社会影响。此外，这项研究将推进科学技术工程和数学教育，包括博士生和本科生研究人员培训，并作为课程材料在界面现象课程。拟议研究的结果将在外联活动中提出，以吸引来自不同背景的学生到工程。此外，研究成果将通过演示向公众传达。细菌将被用作模型系统。这项研究将开发一个通用的框架，以确定所需的活性表面剂的性能，包括轨迹类型，推进强度和表面密度，以产生所需的活性界面层。研究结果将为利用活性胶体层促进乳状液、薄液膜或其他多相体系界面的混合奠定基础。所有的活性胶体都遵循类似的流体动力学描述，本研究将进一步发展。活性胶体在界面附近聚集，可以在界面附近游动，通过流体动力学相互作用捕获，或者可以在粘附状态下游动，其复杂的轨迹在形式和时空意义上都不同于散装的轨迹。 本研究将建立一个游泳者个体在界面上和界面附近的反应库，以通过实验和理论来了解他们的个体行为。本研究将探讨运动在界面，一个二维的活动片，如何传播到相邻的流体。通过了解这些影响，可以建立新的主动接口设计规则，以增强多相系统中的传输。该奖项反映了NSF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。

项目成果

Swimmers at interfaces enhance interfacial transport

• DOI: 10.1039/d4sm00140k
• 发表时间: 2024-06-21
• 期刊: SOFT MATTER
• 影响因子: 3.4
• 作者: Deng，Jiayi;Molaei，Mehdi;Stebe，Kathleen J.
• 通讯作者: Stebe，Kathleen J.

Interfacial flow around a pusher bacterium

推杆细菌周围的界面流

• DOI: 10.1017/jfm.2023.905
• 发表时间: 2023
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Deng, Jiayi;Molaei, Mehdi;Chisholm, Nicholas G.;Stebe, Kathleen J.
• 通讯作者: Stebe, Kathleen J.

Driven and active colloids at fluid interfaces

• DOI: 10.1017/jfm.2020.708
• 发表时间: 2021-03-05
• 期刊: JOURNAL OF FLUID MECHANICS
• 影响因子: 3.7
• 作者: Chisholm, Nicholas G.;Stebe, Kathleen J.
• 通讯作者: Stebe, Kathleen J.

Active Colloids on Fluid Interfaces

• DOI: 10.1016/j.cocis.2022.101629
• 发表时间: 2022-09
• 期刊: Current Opinion in Colloid & Interface Science
• 作者: Jiayi Deng;M. Molaei;Nicholas G. Chisholm;Tianyi Yao;Alismari Read;K. Stebe

Interfacial Flow around Brownian Colloids

• DOI: 10.1103/physrevlett.126.228003
• 发表时间: 2021-06-02
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Molaei, Mehdi;Chisholm, Nicholas G.;Stebe, Kathleen J.
• 通讯作者: Stebe, Kathleen J.