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.

表面张力现象在各种物理过程中是重要的，包括不混溶流体的混合、喷雾和气溶胶的形成以及塑料的发泡。该合作项目涉及颗粒-液体混合物，通常称为颗粒悬浮液。实例包括矿物和陶瓷加工中遇到的浆料、填充颗粒的熔融塑料和印刷油墨。在这样的颗粒悬浮液中，第二不混溶液体的添加由于表面张力和毛细管力而引起颗粒“粘附”和聚集。一个熟悉的例子是沙堡，它的力量来自于小水滴，这些小水滴通过毛细力将沙粒结合在一起。本计画将进行混合流中颗粒间毛细力之基础研究。由毛细力约束的颗粒簇将被放置在定义明确的流动中，并使用自动流动控制的新方法进行研究。这项工作的目的是了解颗粒团簇的流动动力学及其稳定性的限制，这是指由于所施加的流团簇破裂的条件。在过去的十年中，表面张力诱导的颗粒聚集已被用于广泛的材料和材料加工应用，包括大孔陶瓷，3D打印，导电塑料和印刷电子电路。该项目的结果将使合理设计的混合操作，利用毛细管力开发新材料。在多相悬浮液含有颗粒和两个不混溶的液体，毛细管力可以诱导颗粒聚集。所述簇包括由弯月面液体结合的两个或更多个颗粒。在这个项目中，将使用视频显微镜和自动流量控制来研究简单剪切或平面拉伸流场中颗粒团簇的动力学和破裂机制。被称为斯托克斯阱的反馈控制微流体装置将用于使用粘性力精确地操纵颗粒，以创建定义明确的粒子束结合的颗粒簇，并使簇受到精确控制的流动。这项工作的目的是实现一个基本的了解的动力学和破裂的颗粒团在定义明确的流动。该项目将揭示全新的信息，包括粒子团破裂的标准，以及这些标准如何取决于团的组成，弯月面流体的粘度和粒子粗糙度。液/液/粒混合物的混合操作设计目前在本质上是经验性的。该项目将建立基于微观力学的设计规则，用于利用毛细力开发新材料的混合操作。该项目将成为培养研究生和本科生的基础。 两位主要研究者将在本科和大学预科阶段开展大量的外展活动，包括招募代表性不足的群体加入他们的研究小组，以及指导高中生。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.