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

该项目的总体目标，由材料研究部的固态和材料化学计划支持，是发现和开发实现超单分散半导体单壁碳纳米管的新方法。这项工作将探索新的策略，在合成后的分离和排序的纳米管使用纳米管差分共轭聚合物，而在同一时间实现计量的单分散性，需要推进的分化和排序。某些类别的共轭聚合物如聚芴是异常有效的半导体纳米管识别剂，例如通过电子类型如此强大地识别，使得在适当条件下共轭聚合物将不能可测量地分散金属纳米管。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，应该有可能实现这样的纳米管，其单分散性使得它们的带隙多分散性可以仅以百万分之一计，并且它们的电子型多分散性以十亿分之一计（而当前的纳米管单分散性通常以百分之一计）。重点研究将在4个领域进行：（1）探索和实施计量学，可以量化“杂质”纳米管在消失的浓度;（2）基础实验，旨在了解纳米管/区分聚合物结合的材料化学和热力学;（3）研究缺陷对聚合物纳米管结合的作用;（4）实施单步和多步分散以及分散后的差异化。自1991年被发现以来，碳纳米管由于其独特的结构和特殊的性能而吸引了科学家和公众。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，由于纳米管的物理和电子异质性，这一前景尚未实现。最近，发现了一类有前途的聚合物，可用于选择特定类型的碳纳米管，从而大大降低其异质性。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。所获得的理解将被用于制造足够超单分散的碳纳米管，以实现长期以来被炒作但被异质性抑制的应用。结合技术项目，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，并增加代表性不足群体的教育机会。例如，将为中学生创建并实施题为“E3-工程、能源和环境”的基于STEM的实践研讨会。该研讨会将让学生参与具有能源和环境挂钩的材料科学主题（如节能或能量收集材料），教授创造性解决问题，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推广经验。

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.