Multi-Scale Analysis and Simulation of Nanofiber Coatings: Growth and Applications

提案：DMS-0305580PI: Gerald W. Young [gwyoung@uakron.edu]机构：美国阿克伦大学标题：纳米纤维涂层的多尺度分析与模拟：生长与应用摘要本项目提出开发多尺度数学模型和算法来模拟纳米纤维涂层的生长。在过滤、复合材料、生物医药和电子等领域，包覆纳米纤维和纳米纤维芯溶解后形成的纳米管具有潜在的应用前景。对这些高质量纳米材料应用的不断增长的需求推动了对描述涂层过程的模型以及描述制造纳米纤维和纳米管的材料和电磁特性的模型的需求。物理气相沉积法（PVD）对纳米纤维的涂层是一个仅被部分了解的过程。虽然纳米沉积技术的数据已经收集了十多年，但尚未开发出一种全面的涂层过程定量模型。拟议的研究通过概述一个计划来解决这一及时的需求，该计划旨在开发真正的多尺度模型，并在连续长度尺度上模拟涂层的生长，同时与实验验证携手进行。PVD方法允许控制实验条件，以便实验结果和模型预测之间的比较将是直接的。将渐近分析、数值模拟、量子力学和分子动力学结合起来的计划是纳米现象研究的重要一步。这些模型和模拟将连接PVD等离子体反应器中的全局连续体模型、涂层纤维周围的局部纳米尺度模型以及原子尺度上的量子力学和分子动力学模型。这些模型将为涂层生长的宏观比例模型提供输入，以便通过水平集方法跟踪涂层的形态。多尺度建模、仿真和实验工作的总体目标是提供PVD工艺参数如何影响涂层生长的理解，确定控制生长的最佳参数范围，解释涂层生长的实验观察结果，并确定完成产品的有效电磁特性。本项目拟开发多尺度数学模型和算法来模拟纳米纤维涂层的生长。在纳米纤维上涂覆特定材料是一种相对较新的生产纳米纤维和纳米管的工艺（去除纳米纤维芯后的结果）。这些纳米结构在过滤、复合材料、生物医学和电子等领域有许多潜在的应用。本文提出的模型和实验相结合的方法将有助于解决纳米纤维涂层的物理、化学和涂层性能等基本问题。特别是，该项目将提供必要的理解，以控制涂层厚度和均匀性，以生产具有所需尺寸特征的纳米管。除了对科学研究的影响外，该项目还将加强对纳米尺度建模研究生的培训。这对于发展纳米技术的强大工业基础至关重要。这个研究项目将允许阿克伦大学发展必要的专业知识，以扩大现有的项目，包括纳米技术建模的专业化，在研究生和本科生的水平。此外，预计在这项研究中获得的对纳米级制造工艺的增强理解将使制造商能够改进现有产品并开发新产品。

Proposal: DMS-0305580PI: Gerald W. Young [gwyoung@uakron.edu]Institution: University of AkronTitle: MULTISCALE ANALYSIS AND SIMULATION OF NANOFIBER COATINGS: GROWTH AND APPLICATIONSABSTRACTThis project proposes to develop multiscale mathematical models and algorithms for simulating the growth of a coating on a nanofiber. There is potential application for coated nanofibers, and the nanotubes that result after dissolution of the nanofiber cores, in the areas of filtration, composites, biomedicine, and electronics. The ever increasing demand for these high quality nanomaterials applications drives the need for models that describe the coating process as well as models that describe the material and electromagnetic properties of manufactured nanofibers and nanotubes. The coating of nanofibers by physical vapor deposition (PVD) methods is a process that is only partially understood. While data on nanodeposition techniques have been collected for over a decade, a comprehensive quantitative model of the coating process has not yet been developed. The proposed research addresses this timely need by outlining a plan to develop truly multiscale models and simulations of coating growth at the continuum length scale while proceeding hand-in-hand with experimental validation. The PVD method allows for control over the experimental conditions so that comparisons between the experimental results and themodel predictions will be straightforward. The plan to link asymptotic analysis, numerical simulation, quantum mechanics and molecular dynamics constitutes a major step in the study of nanoscale phenomena. The models and simulations will connect global continuum models in a PVD plasma reactor, local nanoscale models around a coated fiber, and quantummechanical and molecular dynamics models at the atomistic scale. These models will provide inputs to a macroscopic scale model of the coating growth so that the morphology of the coating can be tracked via a level set method. The overall goals of the multiscale modeling, simulation, and experimental efforts are to provide an understanding of how PVD process parameters affect the coating growth, to identify an optimal range of parameters for controlling the growth, to explain experimental observations of coating growth that are not well understood, and to determine the effective electromagnetic properties of the completed product.This project proposes to develop multiscale mathematical models and algorithms for simulating the growth of a coating on a nanofiber. The coating of nanofibers with specific materials is a relatively new process for producing coated nanofibers and nanotubes (that result after removing the nanofiber cores). These nanostructures have many potential applications in filtration, composites, biomedicine, and electronics. The proposed combination of modeling and experimental efforts will help to address the fundamental unanswered questions concerning the physics and chemistry of nanofiber coating and the properties of the coating. In particular, this project will provide the understanding necessary to control the coating thickness and uniformity to produce nanotubes with desired dimensional features. In addition to its impact on scientific research, this project will enhance the training of graduate students in nanoscale modeling. This is essential for the development of a strong industrial base in nanotechnology. This research project will allow The University of Akron to develop the expertise necessary to augment existing programs to include a specialization in nanotechnology modeling, at the graduate and the undergraduate level. Further, it is anticipated that the enhanced understanding of nanoscale manufacturing processes gained during this research effort will allow manufacturers to improve existing products and to develop new products.