Collaborative Research: Surfing the order parameter - assembling nanoparticle structures through phase transitions in liquid crystal solvents

这个项目的重点是了解纳米颗粒如何通过分散在液晶中来形成新的结构，如胶囊和泡沫。液晶是液晶显示器中常用的有序流体，但这个项目以一种非常规的方式使用液晶——作为纳米粒子的溶剂。该团队正在研究的新工艺为粒子组装提供了一种快速、可扩展且在很大程度上尚未开发的替代方案。他们正在使用定制的粒子设计，利用高速显微镜和新的计算方法来调整纳米颗粒和液晶之间的相互作用。这项工作计划集中在三个基本的科学问题上：1)粒子是如何被流体输送的？2)颗粒表面处理如何控制结构的形成？3)可能的结构范围是什么？它们是如何选择的？他们正在实验和理论的密切合作中测试一系列的颗粒尺寸、工艺和成分参数。获得对这些新型材料系统的基本理解将对从简单组件中合理设计多尺度结构具有变革性意义。该过程涉及广泛的应用，包括医药、护肤、化妆品和食品科学中的封装技术。UCM是一所西班牙裔服务机构，服务于该州多元化但教育劣势的部分。项目团队致力于指导各级学生学习STEM，通过这种合作，许多研究生和本科生正在接受尖端培训，以提高他们在劳动力市场的竞争力。本科研究是UCM和塔夫茨大学以及SCU的物理项目的一个组成部分，SCU是一个主要的本科院校，具有很强的化学研究传统。UCM正在与塔夫茨大学访问和早期研究学者体验计划（VERSE）合作，从代表性不足的群体中招募学生，在他们的职业生涯早期开始研究。该项目建立的伙伴关系正在三所高等教育机构之间建立研究和教育方面的牢固联系。本项目的重点是了解纳米颗粒在液晶中的物理传输机制，特别是如何利用它们来雕刻纳米颗粒结构。该团队研究的过程以一种非常规的方式利用了液晶，通过使用这种各向异性流体作为纳米颗粒的溶剂，并调节这两种材料之间的相互作用。该工艺为颗粒组装提供了一种快速、可扩展且未开发的替代方案。该团队正在与加州大学默塞德分校和圣克拉拉大学合作，利用默塞德大学的高速荧光显微镜实验和塔夫茨大学的新计算方法，研究这种定制粒子设计的组装过程。工作计划集中在三个基于探究的具体目标上，这些目标需要协同完成：1)粒子如何通过移动相边界传输？2)颗粒表面处理如何控制结构的形成？3)可能的结构范围是什么？它们是如何选择的？然而，该项目有潜力开发一系列新型纳米颗粒结构，并阐明控制结构选择的基本机制，这在很大程度上仍然是未知的。获得基本的理解将是变革性的，能够从简单的组件中合理地设计多尺度结构。该项目通过提供与粒子传输、聚集和纳米科学的广泛应用相关的新过程的基本见解，对软物质社区和其他领域具有广泛的科学影响。该团队利用液晶的化学和/或物理性质自发分离和组织纳米粒子的能力，使用众所周知的材料。该工艺的一个关键特点是结构（和形成机制）只取决于颗粒大小，而不取决于成分。这意味着任何合适的功能化纳米粒子都可以被组装起来，从而扩大了该项目的影响，超出了特定的目标。在广泛的化学环境中实现类似的结构应该是可能的，在医药、护肤、化妆品和食品科学中开辟封装技术。这个项目的模拟代码将作为未来研究的资源影响科学软物质社区。这些代码将作为开源软件传播。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract This project is focused on understanding how nanoparticles can be used to form novel structures such as capsules and foams by dispersing them in a liquid crystal. Liquid crystals are ordered fluids commonly used in LCD displays, but this project uses the liquid crystal in an unconventional way - as a solvent for nanoparticles. The novel process the team are investigating offers a rapid, scalable and largely unexploited alternative for particle assembly. They are using a custom particle design, with high-speed microscopy and new computational approaches to tune the interactions between the nanoparticles and the liquid crystal. The work plan focuses on three fundamental scientific questions: 1) How are particles transported by the fluid? 2) How does particle surface treatment control structure formation? And 3) What range of structures are possible and how are they selected? They are testing a range of particle sizes, and process and compositional parameters in a close collaboration of experiment and theory. Gaining fundamental understanding of these novel material systems will be transformative in enabling rational design of multiscale structures from simple components. The process is relevant to a wide range of applications, including encapsulation technologies in medicine, skincare, cosmetics and food science. UCM is a Hispanic Serving Institution and serves a diverse yet educationally disadvantaged part of the state. The project team is committed to mentoring students in STEM at all levels and through this collaboration numerous graduate and undergraduate students are receiving cutting-edge training to enhance their competitiveness in the workforce. Undergraduate research is an integral part of physics programs at research intensive UCM and Tufts and at SCU, a primarily undergraduate institution with a strong tradition of chemistry research. UCM is partnering with the Tufts Visiting and Early Research Scholars Experience program (VERSE) to recruit students from underrepresented groups to begin research early in their careers. Partnerships created by this project are building a strong link between three higher education institutions in both research and education. Technical Abstract This project is focused on understanding physical transport mechanisms for nanoparticles in liquid crystals and specifically how they can be leveraged to sculpt nanoparticle-based structures. The process the team investigate exploits the liquid crystal in an unconventional way, by using this anisotropic fluid as a solvent for nanoparticles and tuning interactions between these two materials. This process offers a rapid, scalable and largely unexploited alternative for particle assembly. The team is investigating this assembly process using custom particle design in a collaboration between The University of California, Merced and Santa Clara University, with high-speed fluorescence microscopy experiments at Merced and new computational approaches performed at Tufts University. The work plan focuses on three inquiry-based specific aims to be performed collaboratively 1) How are particles transported by moving phase boundaries? 2) How does particle surface treatment control structure formation? And 3) What range of structures are possible and how are they selected? This project has the potential to develop a range of novel nanoparticle-based structures, however, as well as illuminating the fundamental mechanisms governing structure selection which are still largely unknown. Gaining fundamental understanding will be transformative in enabling rational design of multiscale structures from simple components. The project has a broad scientific impact on the soft matter community and beyond by providing fundamental insights into a novel process relevant to a wide range of applications in particle transport, aggregation and nanoscience. The team takes advantage of liquid crystal’s ability to spontaneously segregate and organize nanoparticles by their chemical and/or physical properties using well known materials. A key feature of the process is that the structures (and formation mechanisms) depend only on particle size – not composition. This means that any suitably functionalized nanoparticle can be assembled – broadening the project’s impact beyond the specific aims. It should be possible to achieve similar structures in a broad range of chemical environments, opening up encapsulation technologies in medicine, skincare, cosmetics and food science. Simulation codes from this project will impact the scientific soft matter community as a resource for future investigations. These codes will be disseminated as open-source software.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.