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

技术概述：该项目的主要目标是在材料研究部固态和材料化学计划的支持下，从根本上发现和开发实现超单分散半导体单壁碳纳米管的新方法。这项工作将探索利用纳米管-差异化共轭聚合物在后合成分离和分选纳米管方面的新策略，同时实施量化单分散性的计量学，这是推进差异化和分选所需的。某些类别的共轭聚合物，如多荧烯，是非常有效的半导体纳米管识别剂，例如，通过电子类型的识别非常强大，以至于在适当的条件下，共轭聚合物不会显著分散金属纳米管。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有了更好的了解，应该有可能实现纳米管的单分散性，以至于它们的带隙多分散性只能以百万分之几计算，而它们的电子型多分散性以百万分之几(而目前的纳米管单分散性通常以百分之几来衡量)是可能的。将在4个领域开展重点研究：(1)探索和实施能够在消失浓度下量化“杂质”纳米管的计量学；(2)旨在了解纳米管/差异化聚合物结合的材料化学和热力学的基础实验；(3)研究缺陷对聚合物-纳米管结合的作用；以及(4)实施一步和多步分散和分散后微分。非技术摘要：自1991年发现以来，碳纳米管以其独特的结构和特殊的性能吸引了科学家和普通公众。这些材料有望帮助克服社会在电子、能源和医学方面的许多重大挑战。然而，这一承诺尚未实现，因为纳米管的异质性，既是物理的，也是电子的。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，从而显著降低它们的异质性。这个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。所获得的理解将被用于制造足够超单分散的碳纳米管，以使长期以来被炒作但因异质性而受到抑制的应用程序得以实现。在开展技术项目的同时，还将开展外联活动，鼓励青年进入科学、技术、工程和数学(STEM)领域，并增加代表不足群体的教育机会。例如，将为中学生创建和实施一个以STEM为基础的实践讲习班，标题为“E3-工程、能源和环境”。研讨会将让学生参与与能源和环境挂钩的材料科学主题(如能源效率或能源收集材料)，教授创造性的问题解决方案，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体验。

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.