NIRT: Multi-Scale Simulation of Nanoparticle Aggregation for Scale Up of High-Rate Synthesis Methods

摘要CTS-0403864 R。福克斯，爱荷华州州立大学NIRT：纳米颗粒聚集的多尺度模拟，用于高速合成方法的规模化纳米颗粒是许多新型材料的基本组成部分。在几乎所有的纳米颗粒的高速合成方法中，化学前体通过湍流混合聚集在一起，形成由于表面添加和聚集而快速生长的颗粒核。当合成方法按比例扩大时，纳米颗粒的下一代应用将需要精确控制产品质量。从颗粒表面化学和湍流中随时间变化的剪切速率的详细知识开始预测纳米颗粒聚集是高速率合成方法规模化的关键步骤。在这个项目中，一个由科学家和工程师组成的国际跨学科团队将开发和验证基于基本化学和物理模型的多尺度计算工具，这些工具可以先验地预测在高速率合成方法放大后产生的纳米颗粒簇的性质。计算方法包括颗粒表面化学的量子计算，这些方法包括：（原子到分子尺度）、有和没有剪切的纳米颗粒聚集的布朗动力学模拟（纳米到微米尺度）、湍流中颗粒尺寸分布的直接数值模拟和大涡模拟（微米到宏观尺度）。实验验证方法包括使用原子力显微镜直接测量颗粒间势，使用光散射测量静态系统中的团簇尺寸分布，以及泰勒-库埃特流中团簇尺寸和分形维的原位测量。要研究的模型系统是单分散胶体功能化乳胶纳米颗粒。纳米粒子将在我们的实验室合成，以期仔细调节和理解该系统中的聚集机制。将研究三种类型的功能化纳米粒子：（1）未改性胶乳，（2）磺化胶乳，和（3）羧基化胶乳;和表面覆盖的程度将变化，以探测表面化学对纳米粒子聚集机制的影响。这些功能的添加改性的胶乳颗粒的疏水表面，并能够在未改性和改性的纳米粒子的混合物中的聚集机制的询问。 模型系统的选择也是由我们对表面改性乳胶纳米颗粒之间的表面-表面、表面-分子和分子-分子相互作用进行详细的从头计算的能力驱动的。使用这种对纳米颗粒表面化学的详细原子描述，我们会发展出粗糙的grainedinterparticle势模型，用于布朗动力学模拟，以预测剪切流中的团簇尺寸分布和团簇形态。从这些信息中，聚集所需的Smoluchowski方程的核心将被提取和实施的一般动力学方程的颗粒聚集在湍流。在模型开发的每一步，将进行适当的实验验证测试，以确保多尺度模拟工具与现实相符。拟议活动的知识价值：合理设计和扩大纳米级合成和加工方法是实现纳米颗粒广泛技术应用的商业可行性的关键一步。通过开发和验证多尺度、多现象的模拟工具，该项目将首次展示从基本化学和物理理论模型出发，在规模扩大后预测高速合成方法生产的纳米颗粒性能的能力。这个跨学科的团队聚集攻击这个问题是唯一合格的桥梁的长度和时间尺度的巨大范围，以及相应的数值和实验的挑战，这是需要成功地完成这一任务。拟议的活动的更广泛的影响：该项目将导致在参与大学的纳米科学和技术的新课程的发展。本科教育将通过爱荷华州的计算化学、物理和数学REU项目和明尼苏达大学的外联项目（CoS、APEXES、MCSRO）得到加强。研究生教育将通过与工业和国际合作伙伴的实习计划以及明尼苏达州纳米粒子科学和工程的IGERT来加强。将通过参与爱荷华州的LEAD、Science Bound和PWSE方案以及明尼苏达州的类似方案，积极开展K-12外联和招募少数民族和妇女的工作。该项目的成果将通过工业和国际合作伙伴关系、专业会议的专门会议、年度纳米科学和工程研讨会以及档案出版物广泛传播。研究和教育主题在本建议中涉及：（按重要性排序）1。纳米级的制造工艺2。多尺度、多现象理论、纳米尺度建模与仿真3.环境中的纳米尺度过程

AbstractCTS-0403864R. Fox, Iowa State UniversityNIRT: Multi-Scale Simulation of Nanoparticle Aggregation for Scale Up of High-Rate Synthesis MethodsNanoparticles are the basic building blocks for many novel materials. In nearly all high-rate synthesis methods for nanoparticles, chemical precursors are brought together by turbulent mixing to form particle nuclei that grow rapidly due to surface addition and aggregation. Next-generation applications of nanoparticles will require precise control of product quality when synthesis methods are scaled up. Predicting nanoparticle aggregation starting with detailed knowledge of particle surface chemistry and the time-dependent shear rate in a turbulent flow is the key step for scale up of high-rate synthesis methods. In this project, an international, interdisciplinary team of scientists and engineers will develop and validate multi-scale computational tools based on fundamental chemical and physical models that can predict a priori the properties of nanoparticle clusters produced after scale up of high-rate synthesis methods.The computational approaches range from quantum calculations of particle surface chemistry (atomic to molecular scale), to Brownian dynamic simulations of nanoparticle aggregation with and without shear (nano to micron scale), to direct-numerical and large-eddy simulations of the particle size distribution in turbulent flow (micron to macro scale). The experimental validation approaches range from direct measurements of the interparticle potentials using atomic force microscopy, to measurements of the cluster size distribution in quiescent systems using light scattering, to in situ measurements of cluster size and fractal dimension in Taylor-Couette flow.The model system to be investigated is monodisperse colloidal functionalized latex nanoparticles. The nanoparticles will be synthesized in our lab with a view to carefully modulate and understand aggregation mechanisms in this system. Three types of functionalized nanoparticles will be investigated: (1) unmodified latex, (2) sulfonated latex, and (3) carboxylated latex; and the extent of surface coverage will be varied to probe the effect of surface chemistry on nanoparticle aggregation mechanisms. The addition of these functionalities modifies the hydrophobic surface of the latex particles, and enables interrogation of aggregation mechanisms in mixtures of unmodified and modified nanoparticles. The choice for the model system is also driven by our ability to perform detailed ab initio quantum calculations of surface-surface, surface-molecular, and molecular-molecular interactions between surface-modified latex nanoparticles.Using this detailed atomistic description of nanoparticle surface chemistry, we will develop coarse-grainedinterparticle potential models for use in Brownian dynamics simulations to predict cluster size distribution and cluster morphology in shear flow. From this information, aggregation kernels needed for the Smoluchowski equation will be extracted and implemented in the general dynamic equation for particle aggregation in turbulent flow. At each step of model development, appropriate experimental validation tests will be carried out to ensure that the multi-scale simulation tools agree with reality.Intellectual merit of the proposed activity: The rational design and scale up of nanoscale synthesis and processing methods is a crucial step towards the commercial viability of nanoparticles for widespread technological applications. By developing and validating multi-scale, multi-phenomena simulation tools, this project will demonstrate for the first time the capability to predict the properties of nanoparticles produced by high-rate synthesis methods after scale up starting from the fundamental chemical and physical theoretical models. The interdisciplinary team assembled to attack this problem is uniquely qualified to bridge the enormous range of length and time scales, and the corresponding numerical and experimental challenges, that are required to accomplish successfully this task.Broader impacts of the proposed activity: This project will lead to the development of new courses in Nanoscale science and technology at the participating universities. Undergraduate education will be enhanced through an REU program in computational chemistry, physics and mathematics at Iowa State; and outreach programs (CoS, APEXES, MCSRO) at the University of Minnesota. Graduate education will be enhanced by internship programs with industrial and international partners, and the IGERT for nanoparticle science and engineering at Minnesota. K-12 outreach and recruitment of minorities and women will be actively pursued through participation in the LEAD, Science Bound, and PWSE programs at Iowa State, and similar programs at Minnesota. Results from the project will be disseminated broadly through the industrial and international partnerships, dedicated sessions at professional meetings, annualnanoscale science and engineering workshops, and archival publications. Research and education themes addressed in this proposal: (in order of significance)1. Manufacturing Processes at the Nanoscale2. Multi-scale, Multi-phenomena Theory, Modeling and Simulation at the Nanoscale3. Nanoscale Processes in the Environment