导师序言
Supervisors Foreword
Carbon nanotubes CNTs have drawn intensive research interest during past 25 years for their unique Dirac cone structure which can be refer to as Dirac carbon materials. CNTs are typical onedimensional singlecrystal nanomaterials, they have excellent mechanical, thermal and electrical properties and wide applications. Ultralong CNTs refers to the horizontally aligned CNT arrays which are usually grown on flat substrates, parallel with each other with large intertube distances. They usually have perfect structures, and lengths up to centimeters, even decimeters. Ultralong CNTs are promising candidates as building blocks for next generation high speed chips and sensors, transparent displays, opticalelectronic device, superstrong tethers, aeronautics and aerospace materials, etc. The controlled synthesis of ultralong CNTs with perfect structures is the key to fully exploit the extraordinary properties of CNTs. It has always been a great challenge how to grow macroscale singlecrystals with no defects or monothematic colored. Thus, the synthesis of ultralong CNTs with monothematic colored is of significant importance from both fundamental and industrial aspects.The main aim of this Ph. D. thesis is to develop an innovative CNTs growth and visualization method that can control synthesis of ultralong CNTs with perfect structures and explore their excellent properties. A deep understanding of the CNT growth mechanism is the first step for the controlled synthesis of ultralong CNTs with high quality. The equal deactivation mechanism of SchulzFlory distribution is found can describe the growth mechanism for ultralong CNTs very well, which provide with a theoretical tool to control the defects in the asgrown ultralong CNTs. With these approaches, ultralong highquality CNTs with different structures can be obtained. By completely eliminating the factors which may induce defects in the CNT walls, ultralong CNTs with perfect structures can be obtained. Their chiral indices keep unchanged for several centimeters long along the axial direction of the CNTs.Direct visualization and manipulation of individual carbon nanotubes in ambient conditions is of great significance for their characterizations and applications. With the assistance of TiO2 nanoparticles, individual carbon nanotubes can be easily manipulated under an optical microscope at macroscopic scale and in ambient conditions. With the help of this technology, the asgrown ultralong CNTs exhibit superhigh mechanical strength 100 GPa and their breaking strain 17.5% reach the theoretical limits. Superlubricity is realized in centimetreslong doublewalled carbon nanotubes DWCNTs under ambient conditions by pulling out inner shells of multiwalled carbon nanotubes.We hope that this Ph. D. thesis will shed light on the controlled synthesis of ultralong CNTs with perfect structures and excellent properties. Moreover, the growth mechanism and controlled synthesis of ultralong CNTs with perfect structures as well as the optical visualization, manipulation tool also offers a good model for other onedimensional nanomaterials.
Wei FeiDepartment of Chemical Engineering,Tsinghua UniversityDecember 2016
清华大学校长2017年12月5日
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