Cloaking Anisotropic Capillary Interactions Through Tunable Nanoscale Surface Topography

通过可调纳米级表面形貌隐藏各向异性毛细管相互作用

• 批准号: 2232579
• 负责人: Peter Beltramo
• 金额: $ 38.19万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2232579&HistoricalAwards=false
• 关键词: Cloaking; Anisotropic; Capillary; Interactions; Through

Novel materials, such as solar photovoltaics, antireflective coatings, synthetic membranes, and biosensors, may be engineered for improved performance through the nano- and micro-scale ordering of small particles. Next generation versions of these technologies require ordered two-dimensional structures that have direction-dependent organization. In this project, the research team will investigate a new approach to creating such ordered assemblies of particles using stretched polymer spheres, termed “ellipsoids”. Such particles irreversibly pin to air-water interfaces to conveniently create a two-dimensional layer; however, forces between the particles cause disorganized assemblies to form. This hurdle will be overcome in this project by engineering the interactions between the particles through novel particle synthesis techniques that give the particle surface a controlled degree of roughness. The project will focus on how particle roughness can be designed to dictate the forces between the particles and lead to their ultimate ordered assembly at the air-water interface. By doing this fundamental science, the foundational paradigm to develop two-dimensional materials applicable to a variety of fields, including plasmonics, solar photovoltaics, coatings, membranes, and biosensors, will be established. In addition, several educational and outreach activities are integrated into the project. Undergraduate students from local community colleges will be exposed to opportunities in STEM by recruitment for summer research experiences. The PI will also develop active learning workshops for middle and high school students aimed at increasing interest in STEM fields by exposing students to the exciting real-world applications of particles at interfaces. The project will investigate how nanoscale surface topography (roughness or porosity) dictates the capillary interactions and assembly of anisotropic polymer ellipsoidal particles at fluid interfaces. This work is motivated by the plethora of novel materials (e.g., antireflective coatings, synthetic membranes, hierarchical surfaces, biomimetic materials) enabled from the two-dimensional ordering of anisotropic colloids. However, strong capillary attraction between particles at fluid interfaces dooms anisotropic particle assembly. The central hypothesis is that the capillary forces can be tuned by altering the curvature of the fluid interface surrounding pinned microparticles through the rational design of particles with controlled porosity or roughness. The research team seeks to apply a novel synthetic approach to create polymer ellipsoids with tunable roughness and porosity, quantitatively characterize the capillary interactions between such particles, and ultimately control the microstructural organization of particles whose detrimental capillary interactions have effectively been “cloaked” via their surface topography. First, seeded emulsion polymerization will be used to create biphasic, chemically patchy polymer colloids which can be transformed into rough and porous ellipsoids. Second, the capillary interaction energy between particles will be determined via a combination of monitoring two-particle approach profiles and using Mirau interferometry to measure undulations in particle-liquid contact line with nanometer scale precision. Finally, ordered assemblies will be created using particles with promising interaction energies. By linking the nanoscale particle surface characteristics with interfacial interactions, we will be able to identify design principles for nanoscale surface topography that minimize (i.e., “cloak”) strong capillary interactions to unlock ordered 2D microstructures comprised of anisotropic particles. These well-defined and otherwise inaccessible monolayer assemblies are directly relevant to applications in the fields of energy harvesting, photonics, particle-stabilized emulsions, biological interfaces, membranes, and/or hierarchical materials. The project will include the development of active learning workshops focused on interfacial materials and self-assembly concepts for K-12 educators and school-aged children, as well as expanding access to engineering research opportunities for underrepresented groups through coordination with local community colleges.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.

太阳能光伏电池、抗反射涂层、合成膜和生物传感器等新型材料可以通过小颗粒的纳米和微米级有序化来设计以提高性能。这些技术的下一代版本需要具有方向依赖组织的有序二维结构。 在这个项目中，研究小组将研究一种新的方法，使用拉伸的聚合物球体（称为“椭球体”）来创建这种有序的粒子组装体。这种颗粒不可逆地钉在空气-水界面上，以方便地产生二维层;然而，颗粒之间的力导致形成无序的组件。 在这个项目中，通过新颖的颗粒合成技术来设计颗粒之间的相互作用，使颗粒表面具有可控的粗糙度，从而克服了这一障碍。 该项目将专注于如何设计颗粒粗糙度，以决定颗粒之间的力，并导致它们在空气-水界面上的最终有序组装。通过这项基础科学，将建立开发适用于各种领域的二维材料的基础范例，包括等离子体，太阳能光子学，涂层，膜和生物传感器。此外，该项目还纳入了若干教育和外联活动。来自当地社区学院的本科生将通过招募暑期研究经验来获得STEM的机会。PI还将为初中和高中学生开发主动学习研讨会，旨在通过让学生接触粒子在界面上令人兴奋的现实世界应用，提高他们对STEM领域的兴趣。该项目将研究纳米级表面形貌（粗糙度或孔隙度）如何决定毛细管相互作用和各向异性聚合物椭球颗粒在流体界面的组装。这项工作的动机是大量的新材料（例如，抗反射涂层、合成膜、分级表面、仿生材料）。 然而，在流体界面处的颗粒之间的强毛细吸引力注定了各向异性颗粒组装。 中心假设是，毛细力可以通过改变周围钉扎微粒的流体界面的曲率，通过合理的设计与控制的孔隙度或粗糙度的颗粒来调整。该研究小组试图应用一种新的合成方法来创建具有可调粗糙度和孔隙率的聚合物椭球体，定量表征这些颗粒之间的毛细管相互作用，并最终控制颗粒的微观结构组织，其有害的毛细管相互作用已通过其表面形貌有效地“隐藏”。首先，种子乳液聚合将用于产生双相的、化学上片状的聚合物胶体，其可以转化为粗糙和多孔的椭球体。第二，颗粒之间的毛细管相互作用能将通过监测两个粒子的方法配置文件和使用Mirau干涉测量颗粒-液体接触线的纳米级精度的波动相结合来确定。最后，有序组件将使用具有有希望的相互作用能的粒子来创建。 通过将纳米级颗粒表面特征与界面相互作用联系起来，我们将能够确定纳米级表面形貌的设计原则，以最大限度地减少（即，“斗篷”）强毛细管相互作用以解锁由各向异性颗粒组成的有序2D微结构。 这些明确定义的和以其他方式不可接近的单层组装体与能量收集、光子学、颗粒稳定的乳液、生物界面、膜和/或分级材料领域中的应用直接相关。 该项目将包括为K-12教育工作者和学龄儿童开发以界面材料和自组装概念为重点的主动学习讲习班，该奖项反映了NSF的法定使命，并被认为是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。

项目成果

Nanoscale Porosity in Microellipsoids Cloaks Interparticle Capillary Attraction at Fluid Interfaces

微椭球体中的纳米级孔隙掩盖了流体界面处的颗粒间毛细管吸引力

• DOI: 10.1021/acsnano.3c03301
• 发表时间: 2023
• 期刊: ACS Nano
• 影响因子: 17.1
• 作者: Trevenen, Samuel;Rahman, Md Anisur;Hamilton, Heather S. C.;Ribbe, Alexander E.;Bradley, Laura C.;Beltramo, Peter J.
• 通讯作者: Beltramo, Peter J.

Rough colloids at fluid interfaces: from fundamental science to applications

• DOI: 10.3389/fphy.2023.1248706
• 发表时间: 2023-10
• 期刊: Frontiers in Physics
• 影响因子: 3.1
• 作者: Md Anisur Rahman;P. Beltramo