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Functionally Graded Carbon Nanotubes by Dynamic Control of Morphology during Chemical Vapor Deposition

通过化学气相沉积过程中形态的动态控制实现功能梯度碳纳米管

基本信息

批准号：
1825772
负责人：
Mostafa Bedewy
金额：
$ 33.05万
依托单位：
University of Pittsburgh
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1825772&HistoricalAwards=false
关键词：
Functionally Graded Carbon Nanotubes Dynamic

项目摘要

This grant will support basic research aimed at revealing the fundamental mechanisms underlying the process of manufacturing aligned carbon nanotubes for emerging applications of national interest. Carbon nanotubes are tubes that are smaller than one ten-thousandth of a human hair and can be thought of as atom-thick sheets that are wrapped seamlessly into tubes. The superior chemical and physical properties of individual nanotubes, as well as the collective unique directionality of energy and mass transport through large populations of aligned carbon nanotubes underpin their potential in many critical technological areas. The commercial production of carbon nanotubes exceeds several thousand tons per year and are used in products that rely on the random dispersion nanotubes of various lengths and diameters into a matrix to enhance the composite properties. However, emerging applications such as high power-density devices, 3D nanoelectronics, nanoporous membranes, and structural materials require more precise control of the spatial variation of sizes, order and hierarchical morphology of aligned carbon nanotube ensembles. This research looks to producing, through new understanding of their initial nucleation and subsequent growth, large arrays of vertically aligned carbon nanotubes which are all identical in width and length. These 'forests' of identical nanotubes have excellent mechanical properties and can be used in new application areas where the random length of the nanotubes would lead to poor performance. Research in this project will contribute knowledge towards building the process-structure-property relationship necessary for pushing emerging applications of nanotubes closer to market, leading to enhancing the American economic competitiveness, while advancing university-level education of molecular-scale manufacturing. Public outreach will be facilitated by the continued development of YouTube channel explaining nanotechnology-related topics to a general audience.The collective properties of vertically aligned carbon nanotubes (VACNTs) are dependent on the spatially varying morphology across their macroscopic forest-like structure. However, there is currently a lack of understanding of the mechanochemical factors governing the nucleation kinetics of large CNT populations, leading to an inability to control these variations in a repeatable fashion during the simultaneous growth of billions of CNTs. This project aims at filling this knowledge gap to enable precise control of spatially-engineered VACNTs grown by rapid thermal chemical vapor deposition (RT-CVD) and allow predicting their properties. This will be achieved by experimental growth of VACNTs under periodic growth conditions with in situ monitoring of height kinetics, combined with ex situ X-ray-based morphological characterization and electron microscopy, as well as stochastic modeling of the rates of catalytic activation and deactivation of CNTs nucleating from substrate-bound catalyst nanoparticles. Hence, the results generated from this project will enable predictably tuning CVD-grown CNTs in a process that is relevant to industrial CNT production.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这笔赠款将支持旨在揭示为国家利益的新兴应用而制造定向碳纳米管过程的基本机制的基础研究。碳纳米管是比人类头发的万分之一还小的管子，可以被认为是原子厚度的薄片，无缝地包裹在管子里。单个纳米管优越的化学和物理性能，以及通过大量定向排列的碳纳米管进行能量和质量传输的集体独特方向性，为它们在许多关键技术领域的潜力奠定了基础。碳纳米管的商业生产每年超过数千吨，用于依赖于将不同长度和直径的随机分散纳米管制成基质以提高复合材料性能的产品。然而，高功率密度器件、3D纳米电子学、纳米孔膜和结构材料等新兴应用需要更精确地控制定向碳纳米管系综的尺寸、顺序和分级形态的空间变化。这项研究旨在通过对碳纳米管初始成核和随后生长的新理解，生产出宽度和长度都相同的垂直排列的大型碳纳米管阵列。这些完全相同的纳米管具有优异的机械性能，可用于任意长度的纳米管会导致性能不佳的新应用领域。该项目的研究将有助于建立必要的过程-结构-性质关系，以推动纳米管的新兴应用更接近市场，从而提高美国的经济竞争力，同时促进大学水平的分子规模制造教育。通过继续开发YouTube频道，向普通观众解释与纳米技术有关的话题，将促进公共宣传。垂直排列的碳纳米管(VACNT)的集体性质取决于其宏观森林状结构在空间上的变化。然而，目前对控制大量碳纳米管群体成核动力学的机械力化学因素缺乏了解，导致无法在数十亿个碳纳米管的同时生长过程中以可重复的方式控制这些变化。该项目旨在填补这一知识空白，以实现对快速热化学气相沉积(RT-CVD)生长的空间工程VACNT的精确控制，并能够预测其性能。这将通过在周期性生长条件下进行VACNTs的实验生长，结合原位高度动力学监测，结合非原位X射线形态表征和电子显微镜，以及对从衬底结合的催化剂纳米颗粒成核的碳纳米管的催化激活和失活速率的随机模拟来实现。因此，该项目产生的结果将使CVD生长的碳纳米管能够在与工业碳纳米管生产相关的过程中进行可预测的调整。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。