Collaborative Research: Diameter and Chirality Control Through Regrowth of Single Wall Carbon Nanotubes

智力优势：合成有用数量的均匀（n,m）同一性单壁碳纳米管（SWNT）是一项严峻的挑战，是先进电子应用所必需的，也是高端SWNT应用面临的主要限制。一个有吸引力的途径是分离小批量的给定SWNT，然后切割成“种子”，实现有效的管端催化剂模板，并从末端再生，保持原始的(n,m)-手性。最近令人兴奋的方法包括分子操作和模板，提出解决这种分离和再生挑战，但这些方法本身就很复杂，难以规模化，而且尚不清楚种子手性是否保持，以及再生是否优先倾向于某些物种。我们已经开发了初步数据，表明在SWNT末端反应性模板化生长催化剂是可行的，这为通过更有效和可扩展的过程大幅降低催化剂模板化过程的复杂性提供了潜力。通过在缩短的SWNT“种子”内部装载催化剂，并在适当的条件下添加反应物（例如H2），我们正在生产具有催化剂模板的SWNT“种子”，以便在再生过程中有效延长，同时保持体积均匀分布。两种有效的模板剂包括通过甲烷化的氢或通过反歧化的COB2B。温度是关键，取决于试剂/催化剂对，也取决于管的身份。这种方法在化学上是有意义的，因为它模拟了SWNT本身的生长过程。我们证明了分散的SWNT种子气相再生的原理。优点包括工艺可扩展性，保真度和减少后处理以降低缺陷率。我们还将利用给定（n,m）丰度谱的富含p13pc的SWNT种子来探测再生，以确定是否在种子尖端开始了富含p12pc的再生，并维持了手性。我们将研究再生过程作为不同直径，手性和金属丰度的SWNT的函数，通过：(i)我们之前展示的窄直径分布SWNT的合成和（ii）根据类型，直径和手性由co-PI分选的SWNT。我们已经证明了生产不同（n,m）丰度、窄直径分布和平均直径从0.6到1.7 nm不等的SWNT样品的能力。提议的努力结合了PI在纳米管合成方面的互补专业知识，以及co-PI在纳米管分离和使用光致发光和可调谐激光共振拉曼光谱的定量（n,m）表征方面的广泛专业化。这种结合的专业知识将允许探索我们的再生过程的机制以及优化。机理研究也将利用pi在反应条件下对SWNT生长催化剂的x射线吸收分析方面的工作。更广泛的影响：特定（n,m） SWNT的化学生产将彻底改变SWNT设备行业。要探索的方法是廉价的，需要很少的后处理，并将把高质量的SWNT在更多的研究人员手中。SWNT还为有兴趣从事研究的本科生提供了令人兴奋的材料：我们的活动包括开发一门实验室课程，让来自本地非博士学位授予机构的学生参与一项关于水修复和SWNT与微生物相互作用的研究项目。学生们将看到SWNT是如何制造的，参与水溶性功能化，并在他们的家庭实验室做实验来评估SWNT对目标微生物的毒性。这将与合作项目负责人参与康涅狄格州范围内的纳米技术本科课程开发联系起来。这包括开发康涅狄格大学的“纳米车项目”，在该项目中，AFM显微镜被装载到一辆面包车上，并被送到高中进行现场演示，包括SWNT演示。

CBET-0828771 (collaborative with CBET-0828824)Pfefferle and PapadimitrakopolousIntellectual Merit: Synthesizing useful quantities of uniform (n,m) identity single-walled carbon nanotubes (SWNT) is a serious challenge, necessary for advanced electronic applications and a major limitation facing high-end SWNT applications. An attractive route involves the isolation of small batches of the given SWNT, followed by cutting into "seeds", achieving effective tube end catalyst templating, and regrowth from the ends maintaining the original (n,m)-chirality. Recent exciting methodologies involving molecular manipulation and templating propose to address this separation and regrowth challenge, but these are inherently complex and difficult to scale, and it is not clear whether seed chirality is maintained and whether regrowth preferentially favors certain species. We have developed preliminary data that it is feasible to reactively template the growth catalyst on the SWNT ends, offering the potential for substantial easing of the complexity of the catalyst templating process with a more effective and scalable process. By loading catalyst on the inside of shortened SWNT "seeds", and adding reactant (e.g. H2) at proper conditions, we are producing SWNT "seeds" with catalyst templated for effective lengthening in a regrowth process with the bulk identity distribution maintained. Two effective templating reagents include hydrogen through methanation or COB2B through reverse disproportionation. Temperature is key, and depends on the reagent/catalyst pair and also on the tube identity. This approach makes chemical sense as it mimics the SWNT growth process itself. We present proof of principle of gas phase regrowth of dispersed SWNT seeds. Advantages include process scalability, fidelity and reduced post-processing for lower defect rate. Regrowth also will be probed using P13PC-enriched SWNT seeds, with given (n,m)-abundance profiles, to establish whether P12PC-enriched regrowth is initiated at the seed-tips and chirality is maintained. We will investigate the regrowth process as a function of different diameter, chirality and metallicity of SWNT, produced by: (i) our previously demonstrated synthesis of narrow-diameter distribution SWNT and (ii) SWNT fractionated by the co-PI according to type, diameter and chirality. We have demonstrated the ability to produce SWNT samples with different (n,m)-abundances, narrow diameter distribution and mean diameter varying from 0.6 to 1.7 nm. The proposed effort combines complementary expertise of the PI in nanotube synthesis and the extensive specialization of the co-PI in nanotube separation and quantitative (n,m)-characterization using photoluminescence and tunable-laser resonance Raman spectroscopy. This combined expertise will allow exploring the mechanism of our regrowth process along with optimization. Mechanism studies will also take advantage of the PIs work on X-ray absorption analysis of SWNT growth catalysts under reaction conditions. Broader Impacts: Chemical production of specific (n,m) SWNT would revolutionize the SWNT device industry. The method to be explored is inexpensive, requires little post processing and would put good quality SWNT in the hands of many more researchers. SWNT also provides an exciting material for interesting undergraduates in research: our activities include developing a lab-based course involving students from local non-PhD granting institutions, involving participation in a research project on water remediation and the interaction of SWNT with microbes. Students will see how SWNT are made, participate in functionalization for water solubility, and do experiments in their home lab to assess SWNT toxicity to a target microbe. This will be linked to the Co-PIs involvement in a Connecticut-wide course development in Nanotechnology for undergraduates. This includes developing UConn's "Nanovan-Project", where an AFM microscope is loaded into a van and driven to high schools for live demonstrations including a SWNT demonstration.