Atomic Scale Design of Nanostructures Using In Situ Characterization-Based Kinetic Models

利用基于原位表征的动力学模型进行纳米结构的原子尺度设计纳米材料具有取决于其尺寸、形状和组成的性质，并有可能在可再生能源、通信和医学等具有重大社会影响的应用中创造技术进步。然而，设计具有特定的、所需的尺寸和形状的纳米颗粒仍然是一个巨大的挑战，仍然经常采用试错法来制造具有适当尺寸和形态的纳米颗粒。为了减少苛刻和昂贵的实验室试验的数量，需要对合成机制和预测模型有基本的了解，但目前还缺乏。在这个项目中，Karim博士和Lu博士正在开发预测动力学模型，该模型基于使用微反应器和先进的表征技术“观察”金属纳米颗粒生长所获得的详细化学信息。这项工作为研究生和本科生提供了学习先进的表征工具和参与导致重大技术进步的尖端纳米科学研究的机会。大分子、超分子和纳米化学计划资助了Karim博士和Lu博士在弗吉尼亚理工学院和州立大学的研究，他们正在开发具有纳米颗粒原位表征能力的微流控纳米颗粒成核和生长反应器。这一独特的技术组合集成了热力学、动力学和先进的原位表征工具，开发了一种方法，使具有特定尺寸和形状的金属胶体纳米颗粒的先验设计成为可能。Karim博士和Lu博士使用他们的微流体学方法，以毫秒级的时间分辨率跟踪纳米颗粒的合成，使用原位X射线光谱和动态光散射来确定合成机理和速率。用多种技术测量了金属、配体和溶剂之间的分子结构和相互作用，并结合成核和生长动力学建立了热力学上一致的动力学模型，能够预测前驱体在成核和生长过程中向纳米粒子的演化。这项工作的重点是胶体钯纳米颗粒和用于预测特定纳米颗粒尺寸、尺寸分布和形貌的实验条件的模型的建立。

Atomic Scale Design of Nanostructures Using In Situ Characterization-Based Kinetic ModelsNanomaterials have properties that depend on their size, shape, and composition, and have the potential to create technological advances in applications with significant societal impacts in renewable energy, communication and medicine. However, designing nanoparticles with specific, desired sizes and shapes remains a grand challenge and a trial-and-error approach is still often employed to make nanoparticles with the appropriate size and morphology. To reduce the number of demanding and costly laboratory trials, a fundamental understanding of the synthesis mechanisms, coupled with predictive models, is required but currently is lacking. In this project, Dr. Karim and Dr. Lu are developing predictive kinetic models based on detailed chemical information obtained from "watching" metal nanoparticles grow using microreactors and advanced characterization techniques. The work provides opportunities for graduate and undergraduate students to learn advanced characterization tools and to participate in cutting edge nanoscience research leading to major technological advances. The Macromolecular, Supramolecular and Nanochemistry Program funds Dr. Karim's and Dr. Lu's research at Virginia Polytechnic Institute and State University where they are developing a microfluidic nanoparticle nucleation and growth reactor with in situ nanoparticle characterization capabilities. The unique combination of techniques integrates thermodynamics, kinetics and advanced in-situ characterization tools to develop a methodology for enabling the a priori design of metal colloidal nanoparticles with specific sizes and shapes. Drs. Karim and Lu use their microfluidics methodology to follow the nanoparticles synthesis with millisecond time resolution using in-situ X-ray spectroscopy and dynamic light scattering to determine the synthesis mechanisms and rates. The molecular structures and interactions between the metal, ligands and solvent are measured by a combination of techniques and are used along with the nucleation and growth kinetics to develop thermodynamically consistent kinetic models capable of predicting the evolution of precursors into nanoparticles during the nucleation and growth. The work focuses on colloidal palladium nanoparticles and the formulation of models used to predict the experimental conditions for specific nanoparticle sizes, size distributions and morphologies.