title: Flow-dependent directional growth of carbon nanotube forests by chemical vapor deposition.
abstract: We demonstrated that the structural formation of vertically aligned carbon nanotube (CNT) forests is primarily affected by the geometry-related gas flow, leading to the change of growth directions during the chemical vapor deposition (CVD) process. By varying the growing time, flow rate, and direction of the carrier gas, the structures and the formation mechanisms of the vertically aligned CNT forests were carefully investigated. The growth directions of CNTs are found to be highly dependent on the nonlinear local gas flows induced by microchannels. The angle of growth significantly changes with increasing gas flows perpendicular to the microchannel, while the parallel gas flow shows almost no effect. A computational fluid dynamics (CFD) model was employed to explain the flow-dependent growth of CNT forests, revealing that the variation of the local pressure induced by microchannels is an important parameter determining the directionality of the CNT growth. We expect that the present method and analyses would provide useful information to control the micro- and macrostructures of vertically aligned CNTs for various structural/electrical applications.
authors.affiliation: School of Mechanical Engineering, Sungkyunkwan University, Suwon, Korea.
authors.forename: Hyeongkeun
authors.initials: H
authors.lastname: Kim
authors.forename: Keun Soo
authors.initials: KS
authors.lastname: Kim
authors.forename: Junmo
authors.initials: J
authors.lastname: Kang
authors.forename: Young Chul
authors.initials: YC
authors.lastname: Park
authors.forename: Kyoung-Yong
authors.initials: KY
authors.lastname: Chun
authors.forename: Jin-Hyo
authors.initials: JH
authors.lastname: Boo
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Byung Hee
authors.initials: BH
authors.lastname: Hong
authors.forename: Jae-Boong
authors.initials: JB
authors.lastname: Choi
mesh_terms: D016880:Anisotropy; D003460:Crystallization / Q000379:methods*; D005740:Gases / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D044085:Microfluidics / Q000379:methods*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D005740:Gases; D046911:Macromolecular Substances; D037742:Nanotubes, Carbon