CAREER: Overcoming Heterogeneity: Ultra-monodisperse Semiconducting Carbon with Parts per Million and Billion Polydispersity

技术概述：该项目由材料研究部固态和材料化学项目支持，其总体目标是发现和开发实现超单分散半导体单壁碳纳米管的根本新方法。这项工作将探索利用纳米管分化共轭聚合物进行纳米管合成后分离和分选的新策略，同时实现量化单分散性的计量，这是推进分化和分选所需要的。某些种类的共轭聚合物，如聚芴，是非常有效的半导体纳米管区分剂，例如，通过电子类型识别的能力非常强，以至于在适当的条件下，共轭聚合物不会明显分散金属纳米管。目前，人们对这些聚合物以及它们如何与纳米管相互作用知之甚少。然而，随着对纳米管-聚合物相互作用的材料化学的更好理解，应该有可能实现纳米管的单分散性，其带隙多分散性可以仅以百万分之一计算，其电子型多分散性可以以十亿分之一计算（而目前的纳米管单分散性通常以百万分之一计算）。重点研究将在四个方面进行：(1)探索和实施可以在消失浓度下量化“杂质”纳米管的计量方法；(2)基础实验，旨在了解纳米管/分化聚合物结合的材料化学和热力学；(3)缺陷对聚合物-纳米管结合作用的研究；(4)实行单步、多步分散和分散后分化。摘要：碳纳米管自1991年被发现以来，由于其独特的结构和特殊的性能，一直吸引着科学家和公众的目光。这些材料有望帮助克服电子、能源和医学领域的许多社会重大挑战。然而，由于纳米管在物理和电子上的异质性，这一前景尚未实现。最近，一类很有前途的聚合物被发现，可以用来选择特定类型的碳纳米管，从而大大减少它们的非均质性。该项目将揭示有关纳米管和聚合物之间相互作用的材料化学的基本细节。所获得的理解将用于制造足够的超单分散碳纳米管，以实现长期以来被炒作但被异质性抑制的应用。与技术项目相结合，将开展外联活动，激励青年进入科学、技术、工程和数学（STEM）领域，并增加代表性不足群体的教育机会。例如，将为中学生创建并实施一个名为“e3 -工程，能源和环境”的动手stem讲习班。该研讨会将让学生参与与能源和环境相关的材料科学主题（如节能或能源收集材料），教授创造性解决问题的方法，激励下一代科学家和工程师，并让本科生和研究生参与指导和拓展经验。

TECHNICAL SUMMARY:The overarching objective of this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, is to uncover and develop fundamentally new ways for realizing ultra-monodisperse semiconducting single-walled carbon nanotubes. This work will explore novel strategies in the post-synthetic separation and sorting of nanotubes using nanotube-differentiating conjugated polymers, while at the same time implement metrologies for quantifying monodispersity that are needed to advance the differentiation and sorting. Certain classes of conjugated polymers such as polyfluorenes are unusually effective semiconducting nanotube-discriminating agents, for example discerning by electronic-type so powerfully that under the proper conditions the conjugated polymers will not measurably disperse nanotubes that are metallic. Currently, very little is known about these polymers and how they interact with nanotubes. However, with a better understanding of the materials chemistry of nanotube-polymer interactions, it should become possible to realize nanotubes that that are so monodisperse that their bandgap polydispersity can be counted in only parts per million and their electronic-type polydispersity in parts per billion (whereas current nanotube monodispersity is typically measured in parts per hundred). Focused research will be pursued in 4 areas: (1) Exploration and implementation of metrology that can quantify "impurity" nanotubes at vanishing concentrations; (2) Fundamental experimentation designed to understand the materials chemistry and thermodynamics of nanotube / differentiating polymer binding; (3) Investigation of the role of defects on polymer-nanotube binding; and (4) Implementation of single- and multi-step dispersion and post-dispersion differentiation. NON-TECHNICAL SUMMARY:Since their discovery in 1991, carbon nanotubes have tantalized scientists and the general public, as well, due to their unique structure and exceptional properties. These materials promise to help overcome many of society's grand challenges in electronics, energy, and medicine. However, this promise has not yet been realized because of nanotubes' heterogeneity, which is both physical and electronic. Recently, a promising class of polymers has been discovered that can be used to select for specific types of carbon nanotubes and thereby dramatically reduce their heterogeneity. This project will uncover fundamental details regarding the materials chemistry of the interactions between nanotubes and the polymers. The understanding that is gained will then be used to create carbon nanotubes that are sufficiently ultra-monodisperse to enable applications that have long been hyped but inhibited by heterogeneity. In conjunction with the technical project, outreach will be conducted to inspire youth to enter science, technology, engineering, and mathematics (STEM) fields and increase educational opportunities for under-represented groups. For example, a hands-on STEM-based workshop for middle school students entitled "E3-Engineering, Energy, and the Environment" will be created and implemented. The workshop will engage students in materials science topics with an energy and environmental hook (such as energy efficient or energy harvesting materials), teach creative problem-solving, inspire the next-generation of scientists and engineers, and involve undergraduate and graduate students in mentoring and outreach experiences.