Towards New Synthetic Methodologies for the Preparation of Well-Defined Carbon Nanomaterials

碳纳米材料，如富勒烯、碳纳米管和石墨烯，具有优异的电子和光学性能。然而，许多潜在的应用要求碳纳米材料具有明确的结构和性能，这仍然不能通过传统的合成方法来实现，这些方法是基于碱性碳原料的高温转化。在上一次资助期间，我们开展了一项创新的研究计划，利用温和的条件制备碳纳米材料，使其能够更好地控制其尺寸、形状、功能和化学性质。这种被称为“杂化方法”的新方法，允许我们从反应性的、自组装的含低聚低聚乙炔的构件中制备碳纳米材料，如线性低聚物、大环和星形分子。在这项提案中，我们打算使用我们最近开发的工具来进一步推动混合战略，目的是开发碳纳米材料，更准确地说，是石墨烯纳米带和富碳纳米管，其结构特性(尺寸、形状、宽度、长度、长宽比等)。化学性质可以被精确地调节。我们的战略将提供具有定制光学和电学特性的新型碳纳米材料，这些特性是使用已知合成方法无法获得的。我们制备不同宽度的石墨烯纳米带的策略依赖于制备芳基附加的聚二乙炔(PDA)作为反应前驱体，它将在温和的条件下通过物理刺激(光、温和的热)进行多次环芳构化反应，以获得所需的材料。具有精心选择的官能团的初始PDA将使用自组装低聚乙炔的拓扑化学聚合，或更传统的涉及C-C偶联反应的溶液化学来制备。利用这些方法，还将制备出不同宽度的不对称石墨烯纳米带。富碳纳米管将通过自组装的丁二炔大环的拓扑化学聚合来制备。利用最近发展起来的用于制备共轭大环的共轭二炔复分解反应，将制备出不同尺寸和化学功能的大环。所有新的碳纳米材料都将通过光学和振动光谱、热分析、电子显微镜、电化学和X射线衍射法进行严格表征，以研究其光学、电子和形态性质。最好的材料将作为半导体材料在太阳能电池和场效应晶体管中进行测试。我们为石墨烯纳米带和纳米管提出的合成策略将导致碳纳米材料，目前为止报道的任何其他合成方法都无法获得这种材料。此外，通过微妙的化学修饰，在石墨烯纳米带和富碳纳米管中“按需”改变结构参数可能会产生巨大的影响，特别是在需要“近乎完美”材料的电子行业。尽管如此，在学术界和工业界的材料科学家可以定期使用这些方法之前，需要做大量的基础研究工作。这笔赠款将是我们在碳纳米材料领域做出重大贡献的绝佳机会。由于其跨学科性质，这些项目也将极大地促进HQP的培训，其技能将在以后惠及私营和公共研究实验室。

Carbon nanomaterials such as fullerenes, carbon nanotubes, and graphene, have outstanding electronic and optical properties. However, many potential applications require carbon nanomaterials with well-defined structures and properties that still cannot be reached through conventional synthetic methods, which are based on high-temperature transformations of basic carbon feedstock. During the last funding period, we undertook an innovative research program for the preparation of carbon nanomaterials using mild conditions, allowing better control over their sizes, shapes, functions, and chemical natures. The new approach, called the “hybrid method,” allowed us to prepare carbon nanomaterials from reactive, self-assembled oligoyne-containing building blocks such as linear oligomers, macrocycles, and star-shaped molecules. In this proposal, we intend to use the tools we have recently developed to push the hybrid strategy further with the aim to develop carbon nanomaterials, more precisely graphene nanoribbons and carbon-rich nanotubes, whose structural properties (size, shape, width, length, aspect ratio, etc.) and chemical nature can be precisely modulated. Our strategies will provide novel carbon nanomaterials with customized optical and electronic properties that cannot be acquired using known synthetic methods. Our strategy to prepare graphene nanoribbons with different widths relies on the preparation of aryl-appended polydiacetylenes (PDAs) as reactive precursors that will undergo multiple cycloaromatization reactions using physical stimuli (light, gentle heat) under mild conditions to give the desired materials. The initial PDAs with carefully chosen functional groups will be prepared using either the topochemical polymerization of self-assembled oligoynes, or more traditional solution chemistry involving C-C coupling reactions. Using these methods, asymmetric graphene nanoribbons with different width will also be prepared. The carbon-rich nanotubes will be prepared using the topochemical polymerization of self-assembled butadiyne-containing macrocycles. Macrocycles with different sizes and chemical functions will be prepared using the recently developed conjugated diynes metathesis reaction that will be adapted for the preparation of conjugated macrocycles.All the new carbon nanomaterials will be rigorously characterized using optical and vibrational spectroscopy, thermal analysis, electronic microscopy, electrochemistry and X-ray diffraction to study their optical, electronic and morphological properties. The best materials will be tested as semiconducting materials in solar cells and field-effect transistors.The synthetic strategies we propose for both graphene nanoribbons and nanotubes will lead to carbon nanomaterials that cannot be accessed by any other synthetic methods reported so far. Moreover, “on-demand” variations of structural parameters in both graphene nanoribbons and carbon-rich nanotubes through subtle chemical modifications could have a tremendous impact, especially in the electronics industry where "close-to-perfect" materials are required. Nonetheless, a lot of fundamental research work needs to be done before these methods can be used on a regular basis by materials scientists in academia and industry. This grant will be an excellent opportunity for us to make significant contributions in the area of carbon nanomaterials. Because of their multidisciplinary nature, these projects will also strongly contribute to the training of HQP whose skills will benefit private and public research laboratories later on.