Carbon Nanotubes
History of Nanotubes
• Discovery of
buckminsterfullerene in 1985
sparked interest in other stable
carbon structures
• In 1991 Sumio Iijima discovered
multi-walled carbon nanotubes
and created first protocol for pure
nanotubes
• Carbon “fibers” were seen as
byproducts of catalytic
experiments since 1976
• In 1993 Iijima produced singlewalled nanotubes with diameter
~1nm
History of nanotubes
• M. Endo used a catalytic
chemical vapor deposition
method (1976)
– Not industrially feasible
• Iijima used an arcevaporation method
– Purer product
• Efforts to control diameter,
number of layers and purity
Producing multi-walled nanotubes
• The arc-evaporator apparatus produces the highestquality nanotubes
• The first nanotubes had two layers with diameter
ranging from 3 to 30 nanometers
• Pass 50 amps of current between two graphite
electrodes in a cloud of helium
• Some of the graphite vaporizes on the cathode,
containing carbon nanotubes
Producing single-walled nanotubes
• Pass a carbon-containing gas, like a hydrocarbon,
over a nano-sized metal catalyst (Fe, Ni, or Co)
• Metal particles catalyze the break down of gaseous
molecules into carbon
• Nanotube begins to grow with the metal at one end
• Poorer quality but better for volume production
• Third method comes from vaporizing a metalgraphite target with a laser
• Results in high yield of single-walled nanotubes
Physical Properties of Carbon Nanotubes
• Consists of 6-Membered
Carbon Rings that Form
Long, Thin, Tubular
Structures
• Similar to Graphite
• Three Different
Conformations
•Arm Chair
•Zig-Zag
•Chiral
Physical Properties of Nanotubes II
• The properties of CNTs are
unparalleled by any substance.
• Strength
• Conductivity and Ballistic Transport
– Electrical
– Fourier’s Law
H=(ΔQ/Δt)=k*A*(ΔT/x)
– Thermal conductivity
k=(ΔQ/ΔT)*(1/A)*(x/ΔT)
– Optical
• CTNs will replace common
infrastructures in modern
technology
Applications of CNTs
Commercial
• Commercial applications for CNTs are not really applicable because
of the high cost of CNT production
•Analysts in 2004 originally thought CNT prices would drop to a
reasonable price by the present, but this was far too optimistic
•There’s little doubt that once the purification and assembly
costs go down, CNTs will be wildly used
•In February, a company was able to make relatively large sheets
(6’x3’) and are looking to mass produce by 2012
•There are also some issues with the toxicity of CNTs
•They are normally made with heavy metal catalysts and if they
are not purified properly this can lead to poisoning in biological
systems
•It is still useful to examine its possible functions on a smaller scale
(following slides)
Electronics
• The high thermal conductivity and low current resistance
makes CNTs very valuable to the future of electronics
– Many developers are making smaller and smaller devices and
overheating is a large problem
– They can also be used in electronics for electromagnetic
shielding because it has good electrostatic dissipation properties
• CNTs may also revolutionize the way speakers are
produced.
– A team in China created speakers using CNTs that were
functional over a wide range of sounds including the range of
human hearing
– The CNT film a only a few nanometers thick and is used to make
the sound using an alternating current.
Medicine
• CNTs have many potential applications in the medical
world
– They can be used to generate heat (via radio waves) or as
drug vectoring agents
– Have major implications for tissue engineering
• Can be used for “improved tracking of cells, sensing of
microenvironments, delivering of transfection agents and
scaffolding for incorporating with the hosts body”
• CNTs are ideal for working in nano environments from 1-100 nm.
• Graph below shows how drastically CNT research in the biomedical
field has increased
• CNTs will be most useful as structural supports as tissue
scaffolding, making these tissues stronger and their conductivity
can be used for directed cell growth
Other Applications
• Preposterous
– Space Elevator
• Not Crazy
– Tennis rackets, bikes, handlebars, hockey and lacrosse sticks
– New ultra-light, ultra-strong body armor for soldiers
– CNTs have been used to develop Ultra Capacitors
• Swapping conventional capacitor materials with
sheets of CNTs greatly maximizes surface area and
creates a much more potent capacitor in a smaller
space
Citation
• Barron, A. Khan, M. “Carbon nanotubes: Opportunities and
Challenges”. Advanced Materials and Processes. 2008.
• Xiao, L. Chen, Z. et al. “Flexible, Stretchable, Transparent Carbon
Nanotube Thin Film Loudspeakers”. NanoLetters. 2008
• Bullis, K. “The Ultra Battery” Technology Review. 2006
• Harrison, B. Atala, A. “”Carbon Nanotube applications for tissue
engineering”. Biomaterials. 28(2007): 344-353
• Harris, Peter. "Carbon Nanotubes." A carbon nanotube page. 1 Mar.
2007. Centre for Advanced Microscopy at University of Reading. 1
Dec. 2008 <http://www.personal.rdg.ac.uk/~scsharip/tubes.htm>.
• Ota, Masahiro. "The Carbon Nanotube, a Product of
Nanotechnology." AICHI VOICE (Cutting Edge). 2002. 2 Dec. 2008
<http://www2.aia.pref.aichi.jp/voice/no15/15_cutting_edge.html>.