Biomedical Engineering Reference
In-Depth Information
Primary synthesis methods for SWCNTs and MWCNTs at the
bottom-up approach include arc discharge, laser ablation, chemical
vapor deposition (CVD), pyrolysis, gas phase catalytic growth from
carbon monoxide (HiPco), electrochemical methods [96]. These
synthesis methods provide direct growth of CNTs onto substrates,
mainly coated by catalysts. During nanotubes synthesis, impurities
in the form of catalyst particles, amorphous carbon, nontubular
fullerenes, and non-nanotube material are also produced. This means
that a controlled method for fabrication of carbon nanostructures
and nanomaterials does not exist yet. Thus, subsequent purification
steps are required to separate nanotubes and to remove impurities
that could suppress the advantageous properties of CNTs at
nanoscale. Each of these synthesis techniques has its advantages
and disadvantages, which are discussed in the extensive literature
available on this topic [97-104].
Selected worldwide manufacturers/distributors of CNTs are
listed in the Table 9.3.
Table 9.3
Selected worldwide manufacturers of CNTs and carbon-based
nanomaterials
Manufacturer
Products
Website
Carbon Nanotechnologies, Inc. (USA)
SWCNT, MWCNT
www.cnanotech.com
Nanocyl SA (Belgium)
SWCNT, MWCNT
www.nanocyl.com
Cheaptubes, Inc. (USA)
CNT, Graphene
www.cheaptubes.com
CNT Co. Ltd (South Korea)
SWCNT, MWCNT www.carbonnanotube.biz
Chengdu Organic Chemicals Co. Ltd. (China)
CNT, Fullerenes
www.timesnano.com
Yunnan Guorui Nano-Tech Co. Ltd. (China)
CNT, Fullerenes
www.sinotubes.com
SES Research (USA)
Fullerenes, CNT http://sesres.com
Xintek. Inc. (USA)
CNT, Fullerenes
www.xintek.com
Sigma-Aldrich (Italy)
CNT, Fullerenes
www.sigma-aldrich.com
into the gas stream of
a CVD furnace via HiPco route can produce up to 10 g/day of carbon-
based nanomaterial at high purity with 97% SWCNTs concentration
[105].
The current state of the art of CNTs fabrication focuses on
direct growth of the nanomaterial onto catalyzed substrates with
nanopatterned transition metals (Fe, Co, Ni, etc.). This means that
CNT bundles tend to grow perpendicularly to the catalyzed surface
according to a
Industrial methods incorporating Fe(CO)
5
structure with a dense network of vertically
aligned individual nanotubes [106, 107]. However, there is no
forest-like
