Carbon Nanotube Presentation

7/28/2019 Carbon Nanotube Presentation

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Carbon Nanotubes


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History of Nanotubes

Discovery ofbuckminsterfullerene in 1985sparked interest in other stablecarbon structures

In 1991 Sumio Iijima discovered

multi-walled carbon nanotubesand created first protocol for purenanotubes

Carbon fibers were seen asbyproducts of catalyticexperiments since 1976

In 1993 Iijima produced single-walled nanotubes with diameter~1nm


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History of nanotubes

M. Endo used a catalytic

chemical vapor deposition

method (1976)

Not industrially feasible

Iijima used an arc-

evaporation method

Purer product

Efforts to control diameter,

number of layers and purity


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Producing multi-walled nanotubes

The arc-evaporator apparatus produces the highest-quality 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


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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 metal-graphite target with a laser

Results in high yield of single-walled nanotubes


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Physical Properties of Carbon Nanotubes

Consists of 6-Membered

Carbon Rings that Form

Long, Thin, Tubular

Structures

Similar to Graphite

Three Different

ConformationsArm Chair

Zig-Zag

Chiral


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Physical Properties of Nanotubes II

The properties of CNTs areunparalleled by any substance.

Strength

Conductivity and Ballistic Transport

Electrical

Fouriers Law

H=(Q/t)=k*A*(T/x)

Thermal conductivity

k=(Q/T)*(1/A)*(x/T) Optical

CTNs will replace common

infrastructures in modern

technology


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Applications of CNTsCommercial

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

Theres little doubt that once the purification and assemblycosts go down, CNTs will be wildly used

In February, a company was able to make relatively large sheets

(6x3) and are looking to mass produce by 2012

There are also some issues with the toxicity of CNTsThey 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)


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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 electromagneticshielding 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 ofhuman hearing

The CNT film a only a few nanometers thick and is used to make

the sound using an alternating current.


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Medicine

CNTs have many potential applications in the medicalworld 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 andscaffolding 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 conductivitycan be used for directed cell growth


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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


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Carbon Nanotube Presentation