Highly Parallel Three-Dimensional Microfluidic Systems for Manufacturing Catalytic Nanoparticles

金属纳米颗粒独特的生物学、光学和化学性质推动了几十年对其潜在应用的研究。如果要使这些应用达到能够产生重大社会影响的水平，就必须开发出具有成本效益的技术来生产与工业相关数量的纳米颗粒。今天，用于制造高质量纳米颗粒的化学制造技术仍然处于小生产规模，其成本反映了手工工艺的有限吞吐量和劳动强度。这是因为只有小规模的化学反应才能在整个反应容器中实现均匀的混合条件和均匀的温度，而这是生产均匀、高质量纳米颗粒的必要条件。标准的、大容量的工业化学反应器缺乏均匀的混合和温度分布，往往会产生低质量的颗粒，因此不适合大规模生产高质量的纳米颗粒，例如用于催化。该奖项旨在研究连续流化学微米级反应器，以维持生产高质量纳米颗粒所需的小规模条件，同时允许连续处理，可以自动化并全天候操作。此外，为了将这些微反应器扩展到工业相关条件，本研究研究了大规模并行化，即同时控制许多微反应器的操作以生产大量高质量的纳米颗粒。这项研究工作与一项外展计划相协调，该计划将社区大学生纳入研究，并使这些学生，特别是女性和少数族裔学生能够从事科学和工程职业。用于商业目的的高质量纳米颗粒仍然在实验室规模上制备，基本上是手工制备的。扩大规模的限制是，在液相化学技术中，所得纳米颗粒的大小和单分散性对反应温度和试剂混合条件极为敏感。在目前工业规模的反应器中，即使有搅拌，也不可能保持必要的均匀性。然而，微流控反应器具有固有的良好热均匀性，微滴微流控系统允许快速混合和均质化。该研究方法依赖于微流控反应器中基于离子液体的纳米颗粒合成。在这些反应器中，液滴在氟碳油基载体流中分离。本研究开发的微流体系统将在非常高的胶体浓度下运行，接近50-100 mg纳米颗粒/mL反应溶剂，而传统的液相方法接近2 mg/mL。在本文研究的纳米制造系统中，一个微反应器系统被缩小到16个平行通道。资助的工作是对关键系统参数的科学调查，例如过程监控和反馈控制，必须解决这些问题才能将这样一个并行系统扩展到任意大的容量。

The unique biological, optical, and chemical properties of metal nanoparticles have driven several decades of research into their many potential applications. If these applications are to be realized at a level that will make a significant societal impact, cost-effective techniques for producing industrially relevant quantities of nanoparticles must be developed. Today, chemical manufacturing techniques for high quality nanoparticle fabrication remain at small production scales, with a cost that reflects the limited throughput and labor intensity of a by-hand process. This is because only small-scale chemical reactions can achieve uniform mixing conditions and uniform temperatures throughout the reaction vessel, which are essential conditions for producing uniform, high-quality nanoparticles. Standard, large-volume industrial chemical reactors lack uniform mixing and temperature distribution tend to produce low-quality particles and are therefore an inappropriate route to the scale-up of high-quality nanoparticle manufacturing, for example, for catalysis. This award investigates continuous-flow chemical micron scale reactors as a means to maintain the small-scale conditions necessary to make high-quality nanoparticles while allowing for continuous processing that can be automated and operated around the clock. Further, to scale these microreactors to industrially relevant conditions, this research investigates massive parallelization, i.e., the controlled operation of many microreactors at once to produce large quantities of high-quality nanoparticles. This research effort is coordinated with an outreach program that integrates community college students into research, and makes science and engineering careers accessible to these students, especially women and minority students.High quality nanoparticles for commercial purposes are still prepared at the lab scale, essentially by hand. The limit to scale-up is the fact that in solution-phase chemical techniques, the size and monodispersity of the resulting nanoparticles are extremely sensitive to the reaction temperature and reagent mixing conditions. It is impossible to maintain the necessary uniformity in current industrial-scale reactors even with stirring. Microfluidic reactors, however, have inherently good thermal uniformity and droplet microfluidic systems allow for rapid mixing and homogenization. This research approach relies on ionic liquid (IL)-based nanoparticle synthesis in microfluidic reactors. In these reactors, droplets of IL are separated in a fluorocarbon oil-based carrier stream. The microfluidic system developed in this research will operate at remarkably high colloid concentrations, nearly 50-100 mg nanoparticles/mL reaction solvent, compared to nearly 2 mg/mL for traditional solution phase approaches. In the nanomanufacturing system studied here, a microreactor system is scaled to sixteen parallel channels. The funded work is a science-based investigation of the key system parameters, such as, process monitoring and feedback control, that must be addressed to scale such a parallel system to an arbitrarily large capacity.