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Transcript of NANOTECHNOLOGY
Nanotechnology is a field of the applied sciences that covers the science, engineering and technology, which have to control, handle and process the matter on a nanoscale
Richard Feynman was the first one to mention the possibilities of nanoscience and nanotechnology, in the well-known lecture gave at Caltech, on 29th of December 1959, called "There's plenty of Room at the Bottom"
What is nanotechnology?
Tiny Size - Huge Future
A nanometre is one thousand
millionth of a meter.
The physical and chemical
properties of the matter change
on nanoscale, which is due to
Notwithstanding, atoms are so minuscule
that they are not visible to the naked eye.
In order to could observe the matter on a
nanoscale, are needed microscopes such as :
Scanning tunneling microscopes (STM)
Atomic force microscopes (AFM)
According to Ralph Merkle, nanotechnology is a manufacturing technology with three main objectives:
1) Place each atom in its right place
2) Achieve that almost any structure is consistent with the physical and chemical laws
3) Ensure that the manufacturing costs do not exceed, widely, to the cost of first matters and energy used in the production process
Nanotechnology and nanoscience, generally can be used in all science fields, since it is a new way to
observe, study and analize
in order to get new properties and solve hurdles and challenges, that up to now still being not solved.
They promise ground-breaking and more efficient solutions to the many problems that humanity has to face day after day.
Nevertheless, the concept of nanotechnology is not so widespread socially.
Medicines that work on a nanoscale
Microchips which are capable of performing complex genetic analysis
Combating pests and pollution at a molecular level
Improved photovoltaic techniques for renewable energy sources
Lighter and stronger materials for the defense, aeronautical and automobile industry
Generation of inexhaustible energy sources
Sun protection creams with nanoparticles which absorb UV rays
"Smart" wrappers for the food market, which give products an appearance of fresh and quality food
Investment in nanotechnology
Many developed countries already spend significant resources and funds for research in this technology, since the future of the market in the coming decades is oriented toward nanotechnology, which is already considered the key technology of the 21st century.
Around 40 laboratories worldwide channel large amounts of money for nanotechnology investigations.
About 300 companies have the term "nano" in their names, although there are very few products on the market and these are set aside in concrete and specific applications.
In order to create these new materials, the following aspects must be taken into account:
1) The relation between the atomic and molecular microstructure of the material
2) Its process of manufacturing or processing
3) The resulting properties
4) The performance of its use
New materials are the result of a refinement of conventional materials.
The concept of
can be misleading, as the logical thing is to think that they are "materials which are new". However they are materials which are trying to:
- Improve the existing manufacturing processes
- Reduce the costs
- Achieve the improvements in the security
Science and engineering of materials
According to studies made by the National Academy of Sciences
Science and engineering of materials
are dedicated to the generation and application of knowledge that relates the composition, strucutre and manufacure of the materials with their properties and uses.
These two sciences have become an essential area of knowledge for other sectors.
Researchers who work in this field, study how can they get different and new properties from different combinations of molecules and materials.
They are looking for comprehending the internal and microscopical connection of materials, their properties, their process and how to improve their performance
In order to improve the properties of many exisiting materials and provide them with new physical and chemical properties.
Ferrofluids were discovered during the 1960s by the National Aeronautics and Space Administration (NASA), where scientists were investigating different methods of controlling the liquids in the space.
Fullerenes were discovered by chance in 1985, by professors Harold Kroto, Robert Curl and Richard Smalley.
are molecules composed of a set of carbon atoms, which can be arranged in a
spherical, ellipsoidal or a cylindrical manner
and placed in a symmetrical way.
The most common allotropic forms of carbon are:
Types of fullerenes
All of them are composed of carbon, but each of them presents a different structure and atoms arrangement
Fullerenes can be divided into different types, depending on the amount of carbon atoms they present.
Fullerene C60 or buckminsterfullerene
Fullerene C60 or buckminsterfullerene
The fullerene C60 or bucminsterfullerene is composed of 60 carbon atoms.
It is called in this way, in honor of Richard Buckminster Fuller, who built the a geodesic dome in 1949, which has the same structure as the C60 fullerene.
This material is composed of 12 pentagons and 20 regular hexagons with an atom of carbon at each vertex, and which presents a stable geometric structure thanks to the isolated pentagon rule.
The fullerene C70 has a similar structure to the C60.
It has the same number of pentagons as the buckminsterfullerene, but has a greater number of hexagons
what makes their from slightly more elongated than the C60
Carbon nanotubes were discovered by Sumio Ijima in 1991.
They are atoms arranged in a cylindrical way in an hexagonal network.
There are two types of nanotubes:
- Simple wall or SWCNT
- Multiple wall or MWCNT
Fullerenes have mechanical, electrical, optical, thermal, chemical and many more exceptional properties.
- Chemical properties
Right now, there are not large applications of fullerenes, due to technical problems.
However, there are some researches that have found good applications:
A single perfect carbon nanotube can be between 10 and 100 times stronger and more resistant than steel.
Fullerenes are very good electricity conductors, since they would be able to conduct electricity without any kind of loss.
In medicine, fullerenes could be used to attack cancer cells, through the introduction of antibiotics inside their structure.
There are some researchers who are working with some derivates of fullerenes, which would be able to attack and fight aggainst the immunodeficiency virus, SIDA.
Aerogel was first made by Samuel Stephens Kistler, in 1931.
With this material, he proves that a dry gel contains a solid and continuous network of the same shape and size as a liquid gel.
What is an aerogel?
An aerogel is a colloidal substance similar to gel, in which the liquid component is replaced by a gas.
Its density is very low, approximately 0.003 g/cm³, what makes it to be the solid of the lowest density in the world.
Between 90% and 99.8% of its composition is air. It is thousand times less dense than the glass and only three times denser than the air.
It has got a powerful thermal insulation, since the greatest part of its composition is gas, and gases are not good conductors of heat.
It presents a very high mechanical resistance, since it can support more than 1000 times its own weight.
It is also called
frozen smoke, solid smoke or blue smoke
, due to its semi-transparent nature, however, it has a similar consistency to polystyrene foam.
Aerogel's colour is blue, since it is composed of very small particles, which scatter blue light, in the same way the atmosphere does.
On a nanometric scale, aerogel is a porous material and its porosities or bubbles are approximately 10 nanometres in width.
Due to the large amount of porosities that presents, it is a very good acoustic insulating, since it is a materials that it does not drive very well the sound.
The behaviour of this material, improves in 6 times the capacity of glass, in 3 times the microfiber polyester and the foam and duplicates the microporous silica.
Aerogel can be made with different materials. There are aerogels based on alumina, silica, oxide of zirconium, tin, chromium, carbon, among others.
Special pieces of clothing, which are able to protect from extreme temperatures, eben if they are very high or very low.
Ideal material for building insulation, as a centimeter of aerogel equals to 2.5cm insulating foam or 3.5cm of fiberglass.
It can be used as a sponge to absorb pollutants such as oil, mercury or lead.
The robot that stepped Mars to collect samples was coated with aerogel, in order that the mechanisms of the robot do no get oidized.
NASA has used aerogel to collect interstellar dust with the Stardust probe.
In the field of medicine, aerogel is being used to regenerate human bones in medical treatments.
I t could also be used as an insecticide. By crushing the aerogel, it gets a very fine powder composed of small grains that are able to block the insects tracheae.
What is a ferrofluid?
is a colloidal mixture of
nanoparticles dispersed and stabilized by
in a carrier liquid, which can be an inorganic solvent or simply water and it presents at the same time, fluid and magnetic properties.
Being a colloidal means that it is composed of two phases:
- One that is continuous, smooth and not magnetized:
water or oil
- The other that is dispersed, solid and permanently magnetized:
Ferrofluids can be composed of ferromagnetic or ferrimagnetic materials and the difference between them is their orientation or position and their magnitude.
Magnetite nanoparticles, which are suspended by Brownian motion, are under continuous agitation, that is caused by messy impacts with the carrier liquid's molecules and which are moving continuously by thermal agitation.
The surfactant importance
To achieve the fluidity and stabilization of the ferromagnetic nanoparticles, they must be coated with a
dispersion and stabilizer agent
, usually called
The surfactant prevents the agglomeration of the particles, due to surface tension and magnetic and Van der Waals strengths.
Some of the most commonly used surfactants, though not the only ones, are:
- Oleic acid
- Tetramethylammonium hydroxide
- Citric acid
- Soy lecithin
The typical composition of ferrofluids, usually is a
of ferromagnetic nanoparticles, a
of surfactant and a
of the carrier fluid.
Ferrofluids, although their name seems to indicate otherwise, do not show
, since they do not retain their magnetization in the absence of an external field.
On the macroscale, ferrofluids are permanently magnetic, but when these materials are at a nanometric level, they become
what means that they only behave as magnetic materials in the presence of a megnetic field.
Their rheological properties change in the presence of a magnetic field, that is they are guided in one way or another depending on the field origin.
Ferrofluids act in the Curie law's way, which means that they become
when increasing the field, and turn to be
when elevating the temperature.
they are used in hard drives, in order to avoid that any foreign substance gets inside.
reduce the friction between two bodies.
space vehicle control
cancer detection, contrast agent in magnetic resonance imaging, cancer treatments and blindness prevention.
dissipate the heat produced inside the loudspeakers.
Separation of materials
with different density
Synthesis of a ferrofluid
prepare a ferrofluid using magnetite and achieve its orientation and magnetism in the presence of a magnetic field, in this case, a neodymium magnet.
- Slow addition of NH3 solution
- Excess of NH3 in the final product
- Use of surfactant
- Magnetic particle size
a ferrofluid made of magnetite and oriented and magnetized in the presence of a neodymium magnet.
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