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.

活性胶体是微米尺度的自构物体。它们积聚在界面附近，为界面工程带来了尚未开发的自由度。在这里，将研究主动胶体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，它们在新技术空间（如微型机器人）中很重要，小物体执行诸如移动货物或释放信号之类的任务。活动胶体的领域受到运动细菌的启发，该胶体可能以非凡的速率移动，通常是其大小的距离十倍。也有合成活性胶体。一个重要的例子是带有铂片的聚合物微光珠，它与普通化学物质（如过氧化氢）反应，该化学物质会增强其运动。 普通的胶体不存在活性，用于在流体界面上形成有组织的结构，这些结构在流体界面之间不混合以稳定水乳液中的油，该结构被广泛用来封装个人护理产品中的水中的油性物质并制定药物。流体界面是用于化学反应和分离的特殊环境。例如，如果在流体界面上存在催化剂，则油相中的试剂可以形成更喜欢水相的产品。这有助于绿色过程中的反应和分离。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，包括博士生和本科研究员培训，以及作为界面现象课程的课程材料。拟议研究的结果将在外展活动中提出，以吸引来自不同背景的学生到工程。此外，研究结果将在公众的演示中传达。细菌将用作模型系统。这项研究将开发一个通用框架，以确定所需的活性表面剂性能，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。结果将奠定地面工作，以促进使用活性胶体层的乳液或薄液膜或其他多相系统的界面混合。所有活性胶体遵守类似的流体动力描述，这项研究将会发展。活性胶体在界面附近积聚，可以游泳与它们相邻，被流体动力相互作用捕获，或者可以在粘附状态下游泳，其复杂轨迹与形式和时空含义不同的轨迹不同。 这项研究将通过实验和理论开发一个界面和附近的游泳者的响应库，以了解其个人行为。这项研究将探测界面中的运动如何（二维活性板）传播到相邻的流体中。通过了解这些含义，可以建立主动界面的新设计规则以增强多相系统的运输。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的影响评估标准来通过评估来支持的。

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.