NSF-DFG Confine: Drying-induced assembly of colloidal supraparticles from anisotropic nanoparticles

该项目是通过“密闭空间中的化学和传输（NSF-DFG）”机会获得的，这是一项由美国国家科学基金会和德国科学研究协会（DFG）参与的合作征集。胶体超粒子——由更小的纳米颗粒（NPs）制成的微米大小的球体——是一种多用途材料。具有内部空隙的多孔超粒子因其催化、光子、药物传递和物理吸收特性而受到特别重视。虽然可以使用溶剂干燥在液滴内组装NPs来大规模制造超颗粒，但这些过程知之甚少。该项目将使用计算机建模来解决多孔超粒子如何形成以及如何设计其特性方面的知识差距。此外，还将研究纳米颗粒的形状和表面性质对组装过程和产品超颗粒特性的影响。将开发的模型在缩短学术和工业环境中新材料的研究和开发周期方面具有重大潜力。这种国际合作将培养一支具有全球竞争力的劳动力队伍。该项目还将整合以下活动：(1)通过对STEM中代表性不足的本科生的夏季研究经验，扩大对计算科学的参与；(2)为K-12学生开发关于扩散的虚拟现实教育活动；(3)传播开源软件和培训材料。本项目的目标是建立数学模型，以研究具有相互作用或形状各向异性的干燥诱导纳米粒子（NPs）组装成胶体超粒子。由于这一过程涉及复杂的分子热力学和约束中的非平衡输运，人们对其了解甚少。互补粒子和连续体模型-分别基于多粒子碰撞动力学和经典动态密度泛函理论方法-将被开发和验证。该模型将应用于具有各向异性吸引力的“斑块”NPs和具有各向异性形状的棒状NPs，这些NPs在实现新的多孔超粒子组合方面具有重要的未开发潜力。局部NP密度和取向顺序将被表征，以系统地询问NP性质和加工条件（如干燥速度）如何决定超颗粒中的孔隙率分布。所提出的研究不仅将提高我们设计超粒子的能力，而且还将推进对NPs受限平流扩散过程的基本理解，包括相关过程，如冷冻干燥、过滤和沉淀。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。

This project was awarded through the “Chemistry and Transport in Confined Spaces (NSF-DFG Confine)" opportunity, a collaborative solicitation that involves the National Science Foundation and Deutsche Forschungsgemeinschaft (DFG). Colloidal supraparticles - micrometer-sized spheres made from smaller nanoparticles (NPs) - are versatile materials. Porous supraparticles with internal voids are particularly valued for their catalytic, photonic, drug delivery, and physical absorption properties. While supraparticles can be fabricated at scale using solvent drying to assemble NPs inside liquid droplets, these processes are poorly understood. This project will use computer modeling to address this knowledge gap in how porous supraparticles form and how their properties can be engineered. Furthermore, the nanoparticle shape and surface property effects on the assembly process and the characteristics of the product supraparticles will be investigated. The models that will be developed have significant potential to shorten the research & development cycle of new materials in both academic and industrial settings. This international collaboration will train a globally competitive work force. The project will also integrate activities to (1) broaden participation in computational science through a summer research experience for undergraduates underrepresented in STEM, (2) develop a virtual-reality educational activity on diffusion for K-12 students, and (3) disseminate open-source software and training materials.The goal of this project is to develop mathematical models to investigate the drying-induced assembly of nanoparticles (NPs) with interaction or shape anisotropy into colloidal supraparticles. This process is poorly understood because it involves complex molecular thermodynamics and nonequilibrium transport in confinement. Complementary particle-based and continuum models - based on the multiparticle collision dynamics and classical dynamic density functional theory approaches, respectively - will be developed and validated. The models will be applied to “patchy” NPs with anisotropic attraction and rodlike NPs with anisotropic shape that have significant untapped potential for realizing new porous supraparticle assemblies. The local NP density and orientational order will be characterized to systematically interrogate how both the NP properties and the processing conditions (such as the drying speed) determine the porosity distribution in the supraparticle. The proposed research will not only improve our ability to engineer supraparticles but also advance fundamental understanding of confined advection-diffusion processes for NPs, including related processes such as freeze drying, filtration, and sedimentation.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.