Reacting precursor/solvent microdroplets in confined 2-D microflows for tailored nanomaterials synthesis

火焰喷雾热解(FSP)是一种强大的技术，它可以通过前驱体/溶剂液滴的气溶胶燃烧来合成化学复杂的颗粒。燃烧的微滴本身可以被视为空间受限的微反应器，有许多机械路径参与实现最终产品的尺寸、组成和形态。我们工作的关键思想是超越传统的FSP，进一步将燃烧的微滴限制在Hele-Shaw电池中，在微反应器中创建一种新的微反应器布置。这种装置不仅提供了对初始尺寸相同的燃烧液滴受一维限制影响的化学性质和物理动力学变化的精确基础研究，而且还提供了反应环境的定义和单个微滴的特定参数历史，以便以可扩展、均匀和一致的方式设计具有定制的化学成分和晶体结构的纳米颗粒。该计划的目标是研究受限环境中液滴到颗粒的转化和气相到颗粒的转化的机理，利用反应性多相2D微流系统，在精确可调的环境中控制单个燃烧的液体前体/溶剂液滴。这种沿着微滴路径确定工艺条件的能力应该能够在一个连续的系统中制造高质量和量身定做的纳米颗粒，其输出可以被引导到另一个系统，用于复合材料的在线加工或其他用途。微滴反应器可以获得很大的加热和冷却速度，在远离平衡的条件下影响详细的化学和传输。可以使用温度控制(加热或冷却)的墙来进行单个液滴的研究，以维持燃烧或淬灭反应，其中可以在不同的位置(与不同的停留时间相关)表征液滴和生成的纳米材料(例如，通过取样进行离线层析)，从而测量反应动力学和纳米材料的演变。燃烧液滴可以与相同或不同前体的燃烧/非燃烧液滴结合。该装置可用于多种现场诊断，包括基于激光的光谱分析、高速成像、干涉粒子成像和彩虹折射测量。将进行异地表征和计算建模，以了解、优化和指导实验。Mädler和Tse的团队拥有独特的多学科专业知识，包括燃烧、材料合成、理论和数值建模、工艺工程和先进的表征技术，以及之前的联合工作，以解决拟议的工作。

Flame spray pyrolysis (FSP) is a robust technique that can synthesize chemically complex particles via aerosol combustion of precursor/solvent droplets. The burning microdroplets themselves can be regarded as spatially-confined microreactors, with numerous mechanistic pathways involved in realizing the final product size, composition, and morphology. The key idea of our work is to go beyond conventional FSP, and to further confine the burning microdroplets within a Hele-Shaw cell, creating a novel arrangement of microreactors within a microreactor. Such a device not only offers precise fundamental investigation of the variations in chemical properties and physical dynamics for initially same-sized burning droplets affected by confinement in one-dimension, but also affords the definition of the reaction environment with specific parameter histories for single microdroplets to design nanoparticles of tailored chemical composition and crystal structure, in scalable, uniform, and consistent fashion. The objective of the proposed program focuses on investigating the mechanisms of droplet-to-particle conversion and gas-to-particle conversion in a confined environment by utilizing a reactive multiphase 2D microflow system with controlled individual burning liquid precursor/solvent droplets in precisely adjustable environments. Such ability to define process conditions along a microdroplet’s path should allow unparalleled ability to fabricate high-quality and tailored nanoparticles in a continuous system whose output can be directed into another system for inline processing of composite materials or for other uses. The microdroplet reactor can attain large heating and cooling rates, affecting detailed chemistry and transport in far-from-equilibrium conditions. Individual droplet investigation can be conducted using temperature-controlled (heated or cooled) walls to sustain combustion or quench reactions, where the droplets and as-produced nanomaterials can be characterized (e.g., offline using chromatography by sampling) at different locations (correlating to different residence times), thereby measuring reaction kinetics and nanomaterials evolution. Burning droplets can coalesce with burning/non-burning droplets of same or different precursors. The setup is amenable to a host of in-situ diagnostics, including laser-based spectroscopy, high-speed imaging, interferometric particle imaging, and rainbow refractometry. Ex-situ characterization and computational modelling will be conducted to understand, optimize, and guide the experiments. The team of Mädler and Tse have the unique multidisciplinary expertise consisting of combustion, materials synthesis, theoretical and numerical modeling, process engineering, and advanced characterization techniques, along with previous joint work, to address the proposed work.