Curvature gradient driven assembly of trapped and reconfigurable structures

俘获和可重构结构的曲率梯度驱动组件

• 批准号: 1607878
• 负责人: Kathleen Stebe
• 金额: $ 42.75万
• 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: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607878&HistoricalAwards=false
• 关键词: Curvature; gradient; driven; assembly; trapped

Non-technical AbstratThe ability to organize microscale particles into well-defined structures lies at the heart of our ability to design new soft, reconfigurable materials. Often, external electrostatic or magnetic fields are used to guide particles into positions where they can interact and form structures. This work studies fields that have not been widely appreciated or used in the past. Particles on fluid interfaces deform and increase the area of the interface around them. The product of surface tension and this area increase is an energy field that depends on the curvature of the fluid interface, so particles move along curvature gradients. Through this simple but remarkable fact, the geometry of the interface itself can be used to direct assembly. Here, these fields are studied to identify new ways to form structures difficult to form by conventional means to make new materials whose properties are explored. Graduate and undergraduate students are trained in the course of performing the proposed research, including students in the Louis Stokes Alliance for Minority Participation program, the Advancing Women in Engineering Program and the UPENN MRSEC REU program. New knowledge developed will be incorporated in a graduate course on interfacial phenomena.Technical AbstractThis research seeks to establish new strategies for directed assembly of micron and sub-micron scale particles to go well beyond the usual close packed assemblies. Particle trapped at fluid interfaces interact and migrate along interface curvature gradients via capillarity. These energies drive formation of complex structures strongly correlated with the interface curvature field, influenced by particle-particle interactions. Since soft matter is inherently deformable, such interactions are a natural route to form reconfigurable, tunable assemblies. Different classes of structures are studied using optical microscopy to observe structures, lithographically defined vessels to mold fluid interfaces and magnetic and other probes to perturb the structures and to guide their reconfiguration. Kinetically trapped structures are studied to form colloidal monolayer membranes with voids, dense regions and oriented structures which respond to changes in interface shape. Equilibrated structures are studied to form structures aligned along principle axes of the interfaces and to study their reconfiguration upon interface perturbation. The (dynamics of) structure formation is observed by optical microscopy for particle shapes and sizes selected for the scale of capillary interactions that they excite and their ability to form oriented structures with associated anisotropies in the structural response to perturbation. For both limits, particle positions/ orientations are compared to and correlated with the interface curvature. Observations are compared to appropriate prediction based on, for example, Stokesian Dynamics simulations for trapped structures and Monte Carlo simulations for equilibrated structures.

非技术抽象将微观颗粒组织成明确定义的结构的能力是我们设计新的柔软，可重构材料的能力的核心。 通常，外部静电场或磁场用于将颗粒引导到可以相互作用并形成结构的位置。这项工作研究领域过去曾被广泛赞赏或使用。 流体界面上的颗粒变形并增加周围界面的面积。表面张力和该区域增加的乘积是一个取决于流体界面曲率的能场，因此颗粒沿曲率梯度移动。 通过这个简单但出色的事实，可以使用界面本身的几何形状来指导组装。 在这里，研究了这些领域，以确定新的方法来形成难以通过传统手段形成的结构，以制造探索属性的新材料。在进行拟议的研究的过程中，对研究生和本科生进行了培训，其中包括路易斯·斯托克斯少数民族参与计划的学生，工程学计划的前进女性和Upenn MRSEC REU计划。开发的新知识将纳入有关界面现象的研究生课程中。技术摘要这项研究旨在为定向组装微米和亚微米尺度颗粒的新策略建立新的策略，以远远超出了通常的紧密包装的组件。 被困在流体界面的粒子通过毛细管沿界面曲率梯度相互作用并迁移。 这些能量驱动复杂结构的形成与界面曲率场的相关性，受颗粒粒子相互作用的影响。由于软物质本质上是可变形的，因此这种相互作用是形成可调，可调组件的自然途径。使用光学显微镜研究了不同类别的结构，以观察结构，正版界定的血管，以塑造流体界面以及磁性以及其他探针，以扰动结构并指导其重新配置。研究了动力学捕获的结构，以形成胶体单层膜，该膜具有空隙，密集区域和面向界面形状变化的定向结构。研究了平衡的结构，以形成沿界面的原理轴对齐的结构，并研究其在界面扰动时的重新配置。 通过光学显微镜观察（动力学）形成的（动力学形成）对于它们激发了毛细管相互作用的尺度和尺寸，它们激发了它们的尺寸，并在对扰动的结构响应中形成与相关各向异性的定向结构的能力。对于这两个限制，将粒子位置/方向进行比较并与界面曲率相关。 将观察结果与基于例如陷阱结构的Stokesian动力学模拟和蒙特卡洛模拟的适当预测进行了比较。