Graphene Nanoribbons Through Directed Self-Assembly

加州大学洛杉矶分校化学和生物化学系的伊夫·F·鲁宾教授在化学系大分子、超分子和纳米化学(MSN)计划的支持下，开发了一种仅用光和热从有机小分子原料制备石墨烯纳米带的新方法。该项目致力于一种独特的合成方法，该方法有望扩大聚合物和二维材料的工具箱，同时创造各种成分和宽度可控的石墨烯纳米带。石墨烯是已知的最薄、最坚固的材料之一。它具有良好的导电性、导热性和吸光性。该项目解决了在制造下一代纳米电子器件和重要技术应用的过程中，制备包含各种化学基团的石墨烯纳米带所面临的挑战和限制。参与该项目的学生接受了有机合成、材料表征和器件制造方面的培训。与加州大学默塞德分校(一家西班牙裔服务机构)材料科学与工程系的学生交换项目促进了研究合作，这对两所大学的研究生和本科生的不同群体都有好处。该项目提供了一种新的方法来制造具有其他结构的石墨烯纳米带，否则使用目前可用的自下而上的合成方法很难获得这些结构。该方法利用1，4-二芳基丁二炔单体的拓扑化学聚合来构建相应的聚二乙炔，然后通过一系列环化和脱氢反应在单独的定量步骤中将其热转化为石墨烯纳米带。这种方法具有很强的优势，因为石墨烯纳米带的合成可以在不使用光和热以外的任何试剂的情况下进行。许多自缔合的1，4-二芳基丁二炔，包括杂环化合物的存在，确保了各种石墨烯纳米带的产生，这些纳米带的受控成分和宽度在0.5-2.0 nm之间变化，具体取决于所使用的炔烃前体。该项目解决了制备石墨烯纳米带的一个合成挑战，在合成过程中涉及的两个主要化学转化过程中完全去除了外部化学物质，从而允许在电子设备中原位制备石墨烯纳米带。备受追捧的石墨烯纳米带产品预计将具有与硅类似的特性，带隙在0.5到2.5 eV之间变化，具体取决于纳米带的组成、结构和宽度。这一奖项反映了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。

Professor Yves F. Rubin of the Department of Chemistry and Biochemistry at the University of California-Los Angeles is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry to develop a novel synthetic approach for the preparation of graphene nanoribbons from small organic molecule starting materials using only light and heat. The project addresses a unique synthesis method which promises to expand the toolbox for polymeric and two-dimensional materials while creating a variety of graphene nanoribbons of controlled compositions and widths. Graphene is one of the thinnest and strongest materials known. It exhibits excellent electricity and heat conduction and light absorption properties. This project addresses the challenges and limitations of preparing graphene nanoribbons with various chemical groups incorporated during the fabrication of the next generation of nanoelectronic devices and technologically important applications. The students involved in the project are trained in organic synthesis, material characterization and device fabrication. A student exchange program with the Department of Materials Science and Engineering at UC Merced (an Hispanic serving institution) promotes research collaborations that are beneficial to a diverse group of graduate and undergraduate students from both institutions. The project offers a new approach to making graphene nanoribbons with structures that would otherwise be difficult to access using currently-available, bottom-up synthesis methodologies. The approach utilizes the topochemical polymerization of 1,4-diarylbutadiyne monomers to build the corresponding polydiacetylenes, which are then converted thermally to graphene nanoribbons in a separate, quantitative step via a series of cyclizations and dehydrogenations. This approach has a strong advantage in that the graphene nanoribbon synthesis can be carried out without the use of any reagent other than light and heat. The availability of a number of self-associating 1,4-diarylbutadiynes, including heterocyclics, assures the creation of a variety of graphene nanoribbons of controlled compositions and widths varying between 0.5 - 2.0 nm, depending on the alkyne precursor used. The project resolves one of the synthetic challenges for preparing graphene nanoribbons by completely removing external chemicals during the two main chemical transformations involved in the synthesis, thus allowing for the preparation of graphene nanoribbons in situ in electronic devices. The sought-after graphene nanoribbon products are expected to have properties similar to silicon with bandgaps varying between 0.5 and 2.5 eV, depending on nanoribbon composition, structure and width.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.