SWNT Amplification: A Route to Specific Structure Nanomanufacturing

本研究的目的是确定将单壁碳纳米管（SWNTs）的合成从产生具有不同电子性质（由于直径/手性范围）的管的混合物的工艺转变为可扩展，高产率和高效的制造工艺的可行性，该工艺允许形成特定直径的SWNTs，从而具有电子性质。这样的过程必须允许高的生产速率，对系统的变化是健壮的，并且是可靠的。实现这一目标最有希望的途径是SWNT扩增过程。在类似于DNA聚合酶链反应（PCR）扩增的过程中，单个SWNT附着在催化剂前体上形成SWNT-cat。催化剂前驱体被还原成金属纳米颗粒，在管和颗粒之间产生密切接触。然后引入生长气体开始SWNT的生长。所得到的SWNT可以被切割并重复循环，直到达到所需的SWNT数量。具有特定手性的单个（或小样本）SWNT将生长成一个大体积。尽管SWNT-cat的合成和生长已经取得了成功，但在大规模SWNT扩增成功之前，还需要解决几个问题：(a)转化为SWNT-cat的SWNT百分比很低（50%），(b)生长的SWNT-cat百分比很低，(c)从SWNT-cat中平均增加的SWNT长度很低（300 nm）， (d)单个种子SWNT的分离仅限于富集，以及(e)生长的SWNT的回收和扩增尚未得到证明。我们的初步结果表明，SWNT扩增的原理是可能的，但为了确定该过程的可行性，该过程中的两个关键步骤必须显示出改进的潜力：(a) SWNT活化的化学方法以允许催化剂颗粒的结合，以及(b)了解预先形成的催化剂颗粒的活性要求。21世纪世界面临的最重要的技术挑战是提供可持续和普遍可用的能源。除了对现有技术进行节约和逐步改进外，解决全球能源问题还需要革命性的新技术。由于预计全球人口将从2004年的65亿增加到2050年的100多亿，每年将需要30-60亿瓦的能源。高效电网的关键技术组成部分是电力电缆（量子导体），它可以重新布线输电网，实现大陆甚至全球的电能传输。扶手椅型SWNT是一种为低损耗电力电缆提供潜在技术解决方案的材料。如果SWNT放大可以从单个步骤的演示转移到一个完整的过程，那么制造量子线导体的能力就可以成为现实。通过这个项目，研究生将获得纳米技术的跨学科教育。将鼓励每个人参加一次国家或国际会议。通过莱斯大学贝克公共政策研究所，PI积极参与能源项目和能源政策。这种互动将使学生能够与政府、行业和学术界的成员一起参与广泛的智力项目。莱斯大学在swnt的侧壁功能化方面拥有重要的专业知识，Barron研究小组与碳纳米管实验室的小组有着积极的互动。

The objective of this study is to determine the feasibility of transforming the synthesis of single walled carbon nanotubes (SWNTs) from a process resulting in a mixture of tubes with different electronic properties (due to a range of diameter/chirality), to a scaleable, high yield, and efficient manufacturing process that allows for the formation of SWNTs of a particular diameter and hence electronic property. Such a process must allow for a high rate of production, be robust to system changes, and reliable. The most promising route to accomplish this goal is the process of SWNT amplification. In an analogous process to polymerase chain reaction (PCR) amplification of DNA, a single SWNT is attached to catalyst precursor forming a SWNT-cat. The catalyst precursor is reduced to form a metal nanoparticle creating intimate contact between the tube and particle. A growth gas is then introduced to begin growth of the SWNT. The resulting SWNT can be cut and the cycle repeated until the quantity of the desired SWNT is reached. The single (or small sample of) SWNT with a particular chirality would be grown into a large volume. In spite of the successful demonstration of SWNT-cat synthesis and growth there are several issues that must be addressed before large-scale SWNT amplification can succeed: (a) the percentage of SWNTs that are converted to SWNT-cat is low (50%), (b) the percentage of SWNT-cat that grows is low, (c) the average increase in length of the SWNT from SWNT-cat is low (300 nm), (d) the separation of individual seed SWNTs is limited to enrichment, and (e) the recycling and amplification of the grown SWNTs has not been demonstrated. Our initial results have demonstrated that the principle of SWNT amplification is possible, but in order to ascertain the viability of the process two of the key steps in this process must show potential for improvement: (a) chemical approaches to SWNT activation to allow binding of a catalyst particle, and (b) understanding of the requirements for activity of a pre-formed catalyst particle. The most important technical challenge facing the world in the 21st century is providing sustainable and universally available energy. In addition to conservation and evolutionary improvements in existing technologies, a solution to the global energy problem will require revolutionary new technology. With a projected increase in the global population from 6.5 billion in 2004 to over 10 billion in 2050 there will be a need for 30-60 tera watts of energy per year. The key technical component of a highly efficient power grid is power cables (quantum conductors) with which to rewire the electrical transmission grid and enable continental, and even worldwide, electrical energy transport. One material that offers a potential technical solution for low loss power cables is the armchair SWNT. If SWNT amplification can be moved from a demonstration of individual steps to a complete process then the ability to manufacture quantum wire conductors can be a reality. Through this project the graduate students will gain a cross-disciplinary education in nanotechnology. Each will be encouraged to participate at one national or international meeting. Through the Baker Institute for Public Policy at Rice the PI is actively involved in energy programs and energy policy. This interaction will allow students to become involved across a broad intellectual program with members of government, industry and academia. Rice University has significant expertise in the sidewall functionalization of SWNTs and the Barron Research Group has an active interaction with the groups of the Carbon Nanotube Laboratory.