Collaborative Research: Micromechanics of Meniscus-bound Particle Clusters

合作研究：弯月面束缚粒子簇的微观力学

• 批准号: 2031144
• 负责人: Lei Li
• 金额: $ 29.2万
• 依托单位: University of Pittsburgh
• 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: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2031144&HistoricalAwards=false
• 关键词: Collaborative; Research; Micromechanics; Meniscus; bound

Surface tension phenomena are important in a variety of physical processes including blending of immiscible fluids, formation of sprays and aerosols and foaming of plastics. This collaborative project concerns particle-liquid mixtures that are generally called particulate suspensions. Examples include slurries encountered in mineral and ceramics processing, particle-filled molten plastics, and printing inks. In such particulate suspensions, the addition of a second immiscible liquid induces particle "sticking" and aggregation due to surface tension and capillary forces. A familiar example is a sandcastle whose strength comes from small water droplets which bind the sand grains together by capillary forces. This project will conduct fundamental studies of interparticle capillary forces in mixing flows. Particle clusters bound by capillary forces will be placed in well-defined flows and studied using new methods in automated flow control. This work aims to understand the flow dynamics of particle clusters and the limits of their stability, which refers to the conditions under which clusters rupture due to the applied flow. Over the past decade, surface tension-induced particle clustering has been exploited for a wide range materials and materials-processing applications including macroporous ceramics, 3D printing, conductive plastics, and printing electronic circuits. The results of this project will enable rational design of mixing operations that exploit capillary forces to develop new materials.In multiphase suspensions containing particles and two immiscible liquids, capillary forces can induce particle clustering. The clusters comprise two or more particles bound by a meniscus liquid. In this project, the dynamics and rupture mechanics of particle clusters in simple shear or planar extensional flow fields will be studied using video microscopy and automated flow control. A feedback-controlled microfluidic device known as a Stokes trap will be used to precisely manipulate particles using viscous forces, to create well-defined meniscus-bound particle clusters, and to subject the clusters to precisely controlled flows. This work aims to achieve a fundamental understanding of the dynamics and rupture of particle clusters in well-defined flows. The project will reveal fundamentally new information, including the criteria for rupture of particle clusters, and how these criteria depend on the composition of the cluster, viscosity of the meniscus fluid, and particle roughness. Thedesign of mixing operations for liquid/liquid/particle mixtures is presently empirical in nature. This project will establish micromechanics-based design rules for such mixing operations that exploit capillary forces to develop new materials. The project will form the basis for training of graduate and undergraduate students. The two principal investigators will conduct numerous outreach activities at the undergraduate and pre-college level, including recruitment of underrepresented groups into their research groups, and mentorship of high-school students.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.

表面张力现象在多种物理过程中很重要，包括混合不混溶的液体，喷雾和气溶胶的形成以及塑料的泡沫。该协作项目涉及通常称为颗粒悬浮液的颗粒液混合物。例子包括矿物质和陶瓷加工，充满颗粒的熔融塑料和印刷油墨中遇到的浆液。在这种颗粒悬浮液中，由于表面张力和毛细作用力，添加第二个不混溶的液体会诱导颗粒“粘着”和聚集。一个熟悉的例子是一个沙堡，其强度来自小水滴，这些水滴将毛细管部队结合在一起。该项目将在混合流中对颗粒毛细管的基本研究。由毛细管绑定的粒子簇将放置在定义明确的流中，并使用自动流控制中的新方法进行研究。这项工作旨在了解粒子簇的流动动力学及其稳定性的极限，这是指由于施加流动而导致的簇破裂的条件。在过去的十年中，表面张力引起的粒子聚类已被利用用于广泛的材料和材料处理应用，包括大孔陶瓷，3D打印，导电塑料和印刷电子电路。该项目的结果将使混合操作的合理设计能够利用毛细作用力开发新材料。在包含颗粒和两个不混溶液体的多相悬浮液中，毛细管可以诱导颗粒聚类。该簇包含两个或多个粒子，由弯面液液体绑定。在这个项目中，将使用视频显微镜和自动流控制研究粒子簇的动力学和破裂力学。被称为Stokes陷阱的反馈控制的微流体设备将用于使用粘性力精确地操纵颗粒，以创建定义明确的半月板结合的粒子簇，并将簇放在精确控制的流动中。这项工作旨在实现对粒子簇在定义明确的流中的动力学和破裂的基本理解。该项目将揭示从根本上揭示的新信息，包括粒子簇破裂的标准，以及这些标准如何取决于簇的组成，半月板流体的粘度和粒子粗糙度。液体/液体/颗粒混合物的混合操作的特征目前是经验的。该项目将建立基于微力学的设计规则，用于利用毛细管力开发新材料的这种混合操作。该项目将构成培训研究生和本科生的基础。 两名主要调查人员将在本科和大学前级别进行众多宣传活动，包括招募代表性不足的小组进入其研究小组，并获得高中生的指导。该奖项反映了NSF的法定任务，并被视为值得通过的支持。使用基金会的智力优点和更广泛的影响评估标准进行评估。

项目成果

Low viscosity liquid bridges: Stretching of liquid bridges immersed in a higher viscosity liquid

低粘度液桥：浸没在较高粘度液体中的液桥的拉伸

• DOI: 10.1016/j.jciso.2023.100079
• 发表时间: 2023
• 期刊: JCIS Open
• 作者: Lopez, Ramon;Vaswani, Jovina;Butler, Dylan T.;McCarthy, Joseph;Velankar, Sachin S.
• 通讯作者: Velankar, Sachin S.