Yung Joon Jung
Ahmed Busnaina, Teiichi Ando, Moneesh Upmanyu, Latika Menon
Date of Award
Doctor of Philosophy
Department or Academic Unit
College of Engineering, Department of Mechanical and Industrial Engineering
mechanical engineering, materials science, carbon nanotube, composites, synthesis
Chemical vapor deposition (CVD) techniques are becoming a strong manufacturing route for the controlled synthesis of single walled carbon nanotubes (SWNTs) especially towards on controlling their structures (diameter and chirality) and building organized SWNT networks with desired growth orientation, position and density. In this dissertation, I investigated various growth parameters in an ethanol CVD system to grow high density and vertically aligned SWNTs with the control over their structure. In particular, the roles of catalyst nanoparticles, aluminum buffer layer, and hydrocarbon source flow rate were intensively studied for the selective growth of vertically aligned SWNTs with a controlled diameter. For this, a unique Raman Radial Breathing Mode (RBM) mapping technique was developed to obtain large area spatial distribution of SWNTs diameters. The fundamental mechanism of diameter selective growth of SWNTs during CVD process was discussed. The study shows that a lower flow rate of carbon source makes a smaller nucleation site for a SWNT resulting in a smaller diameter formation. On the other hand, a higher flow rate of carbon source forms a larger nucleation site growing a SWNT with the larger diameter. The developed highly controlled ethanol CVD system was also used to grow SWNTs on the surface of silica nanoparticles having different bundle size. It is found that precisely confined size of catalyst clusters where SWNTs can grow enables us to grow SWNTs with the controlled bundles size.
SWNTs - polymer composites represent an attractive, emerging class of material, with properties that can approach extraordinary electrical, thermal, mechanical and optical characteristics of SWNTs. This work also demonstrates a novel strategy to fabricate highly organized three dimensional SWNTs structures-polymer hybrid architectures using vertically aligned SWNTs that were developed during my Ph. D. study. Various designs of PDMS/vertically aligned SWNTs hybrid structure were fabricated by using a PDMS casting transfer method. These multi - dimensional micro scale SWNTs architectures - polymer hybrid structures have immediate and immense implications for the development of micro scale multifunctional flexible electromechanical systems such as sensors, smart filters, actuators, interconnects, transparent flexible electrodes, advanced micro-fluidic systems, and smart membrane devices.
Myung Gwan Hahm
Hahm, Myung Gwan, "Controlled synthesis of vertically aligned carbon nanotubes and fabrication of their diverse composites structures" (2010). Mechanical Engineering Dissertations. Paper 11. http://hdl.handle.net/2047/d20000950
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