EAGER: Synthesis of One-Dimensional Carbon Chains by Selective Bond Breaking in Polymers

目的：历史上人们对不同维度结构的碳同素异形体(如三维钻石、二维石墨和碳纳米管轧制的石墨片以及零维富勒烯)进行了大量的研究。然而，一维碳链(卡宾)长期以来在科学界一直是一个鲜为人知的领域，因为缺乏足够大小和定义明确的卡宾晶体样品。该项目的主要目标是通过激光辅助合成工艺从聚合物前体聚噻吩制得卡宾。这项研究不仅有可能通过首次详细描述卡宾的晶体和电子结构来丰富碳谱的科学知识，而且还可能为全碳电子学提供潜在的新技术途径。该项目的目标将通过五个目标实现：1)开发一种利用激光诱导选择性断键从聚噻吩制得卡宾的合成方法；2)生产可规模化的、定义明确的大小结晶卡宾；3)提高卡宾晶体的稳定性；4)澄清晶体卡宾的晶体和电子结构；以及5)了解卡宾的基本物理性质。等电点分析表明，通过破坏聚噻吩中的C-S键和C-H键，可以制备碳链纳米晶。原子力显微镜和X射线衍射仪的测量表明，形成具有准一维碳链结构的立方碳纳米晶是可能的。基于这些初步结果，PI将利用共振激光激发选择性地断裂聚噻吩中的C-S键，这有望产生大量具有明确结构的大小的卡宾晶体。此外，PI还将对卡宾晶体进行结构表征，并使用扫描隧道显微镜研究其电子性质。卡宾晶体的基本物理性质将被相应地研究，以评估在全碳电子中潜在应用的可能性。智力价值：这项研究将建立一种最先进的方法来制备可伸缩数量的大小、定义明确的卡宾晶体。成功的实施可能会推动全碳电子产品的发展。与目前使用的工艺相比，将开发的工艺具有以下优点：1)该方法消除了危险溶液，对环境友好；2)通过获得定义明确的卡宾晶体，卡宾的晶体结构将得到很好的表征；3)该工艺成本效益高，因为它只需一步操作，满足了卡宾晶体的制造需求。由于PI以前成功地开展了激光与聚合物相互作用的研究，最近开发的工艺和表征设备将用于该项目，并将产生更广泛的影响：该项目将使社会和教育界受益。晶态卡宾的大规模生产将为全碳电子、集光天线、抗氧化剂和防腐剂材料等广泛的工程应用提供知识基础和实用途径。研究成果将通过互联网、期刊论文和会议等多种方式向科学界、工业界和公众发布。这一新知识将被纳入内布拉斯加州大学林肯分校的课程(即《电子电气952：纳米技术导论》)。一名来自少数族裔群体的研究生和两名本科生将参与这个项目。

0944479LuGoal & Objectives: Historically, carbon allotropes of different dimensional structures (e.g., 3-D diamonds, 2-D graphite and carbon nanotubes - rolled graphitic sheets, and 0-D fullerenes) have been copiously studied. However, 1-D carbon chains (carbyne) have long been an unfrequented zone in scientific community due to the absence of sufficient sizeable and well-defined carbyne crystal samples. The primary goal of this project is to produce carbyne from a polymeric precursor 'polythiophene' through laser-assisted synthesis process. This research has the potential to not only enrich scientific knowledge of the carbon family tree by enabling for the first time a detailed characterization of the crystal and electronic structures of carbyne, but also allow for the potential new technological approaches to the all-carbon electronics. The goal of this project will be accomplished through five objectives: 1) to develop a synthesis method to obtain carbyne from polythiophene using laser-induced selective bond-breaking; 2) to produce well-defined and sizeable crystalline carbyne in scalable quantities; 3) to improve stability of carbyne crystals, 4) to clarify crystal and electronic structures of crystalline carbyne; and 5) to understand the fundamental physical properties of carbyne. The PI has shown that carbon-chain nanocrystals could be prepared by breaking the C-S and C-H bonds in polythiophene. Atomic force microscopy and X-ray diffraction measurements suggested that the formation of cubic carbon nanocrystals with a quasi-1-D carbon-chain structure is possible. Based on these preliminary results, the PI will selectively break the C-S bonds in polythiophene using resonant laser excitation, which is anticipated to produce sizeable carbyne crystals with well-defined structures in scalable quantities. Furthermore, the PI will carry out structural characterization of the carbyne crystals and investigate the electronic properties using scanning tunneling microscopy. Fundamental physical properties of the carbyne crystals will be investigated correspondingly to evaluate the possibility of potential applications in all-carbon electronics. Intellectual Merit: This research will establish a state-of-the-art approach to preparing sizeable well-defined carbyne crystals with scalable quantities. Successful implementation could advance all-carbon electronics. Compared to currently used processes, the process to be developed has these advantages: 1) the proposed method is environmentally friendly by eliminating hazardous solutions; 2) by obtaining well-defined carbyne crystals, the crystalline structure of carbyne will be well characterized; 3) the process is cost-effective because it requires only a single step, meeting manufacturing needs of carbyne crystals. Because the PI has successfully undertaken previous research on laser interactions with polymers, the process and characterization equipment recently developed will be used in this project Broader Impacts: This project will benefit social and educational communities. The mass-production of crystalline carbyne would provide a knowledge base and practical approaches for a wide range of engineering applications, such as the all-carbon electronics, light harvesting antenna, and antioxidant and anticorrosive material. The research results will be released to scientific, industrial, and public communities in various ways, including the internet, journal papers, and conferences. This new knowledge will be incorporated into courses at the University of Nebraska-Lincoln (i.e., 'ELEC 952: Introduction to Nanotechnology'). One graduate student from an underrepresented minority group and two undergraduate students will work on this project.