DONE BY: OOI XUN YUAN 3I319

nano-Particlesnano-Technology

nano-World

WHAT IS THE NANO-WORLD?

The world influenced by nanotechnology. Nanotechnology is the study of very

minute objects, where the size of such objects range to as small as one out of a billion meter. 1 nanometer = 1/1,000,000,000 meter

It is also very diverse, and thus, as the word ‘nano’ suggests, it is the technology that allows scientists to control matter on the atomic scale.

NANO-PARTICLES

Nano-particles are defined to be small objects that behave as a small unit in terms of transport and properties.

They may or may not exhibit size-related properties that differ significantly from those observed in fine particles or bulk materials.

NANO-PARTICLES

Their properties change together with a change in their sizes.

Heating these nanoparticle arrays also introduce instability into the structures, since smaller nanoparticles start to melt first.

E.g.: Using this method, a nanowire 10 times thinner than any wire, which is important in industries where appliances cannot be too big.

WHY ARE THEY IMPORTANT?

For quality-control: When objects become very small till it cannot be

seen with the naked eye, it is very hard to control it.

The nano-world created thus allows us to see and access these minute objects, and allows us to take control of it.

E.g.: In medicine, virus are usually very small and hard to detect. Only by controlling them through the nano-world can we find ways to fight these viruses.

WHY ARE THEY IMPORTANT?

For further research: Nano-particles are also seen to act as a

bridge between bulk materials and atomic or molecular structures, generating great scientific interest.

This is because particles have different properties and act differently when its size is 1 micrometer and larger (bulk materials) or 1 nanometer and smaller (atomic structures)

WHY ARE THEY IMPORTANT?

For manufacturing more applications: With nano-particles, they can be

introduced into a matrix to allow an object to obtain a more accurate set of properties for certain industries

For instance, nano-particles can be introduced to alter the hardness, the electrical or heat insulation of an object.

EXAMINING THE NANO-GOLD

NANO-GOLD (PROPERTIES)

Also known as colloidal gold A suspension of sub-micrometer-sized

gold particles in a fluid – usually water Not gold in colour, unlike what people

may think, as its reduced particles can now absorb green light, reflecting only red light and is red in colour

Exhibit magnetism, unlike normal gold, which are not magnetic

Aqueous nano-gold

NANO-GOLD (PROPERTIES)

Loses its inertness when shrunk to around 3nm ~ 5nm, acting as excellent catalysts

If it is any bigger or smaller than that, it would regain its inertness

One such reaction is the conversion of carbon-monoxide (CO) to carbon-dioxide (CO2). Nano-gold catalyzes this reaction at room temperature and with 100-percent efficiency.

This can be applied to firefighting jobs, where they might have to extinguish fires which have incomplete combustions, and the catalysts help to convert the poisonous CO to CO2.

NANO-GOLD (EXPLANATION)

Interesting discoveries have been made along the way to explain the varying properties that nano-gold has.

However, none of them had been concrete enough, and can only partially explain some of the phenomena.

NANO-GOLD (EXPLANATION)

The bond-order-length-strength (BOLS) correlation mechanism:

It indicates that the broken bond induced local strain and quantum trapping and the associated densification of charge and energy in the surface skin are responsible for the size-induced behaviour.

Having shorter and stronger bonds in the surface skin lowers the energy levels and increase the elecronegativity of electrons, hence atoms would take in electrons easily.

This helps to explain why nano-gold are such great catalysts.

WHAT IT IS USED FOR

Electron Microscopy: The nano-gold particles can be

attached to many traditional biological probes.

These particles can be manipulated and easily differentiated due to its varying properties when their sizes are changed.

Hence, it can be used in electron-microscopes, where very small objects are observed.

WHAT IT IS USED FOR

Health and medical applications: Used as a therapy for rheumatoid

arthritis in rats. Implantation of gold beads near

arthritic hip joints in dogs has been found to relieve pain.

Colloidal gold can even be used to target tumours and provide detection in cancer research.

VENTURING INTO OTHER NANO-MATERIALS…

CARBON NANOTUBES (PROPERTIES)

Allotropes of carbon with a cylindrical nanostructure.

Categorized as a fullerene: They are molecules totally composed of only carbon atoms. Hence it is insoluble in water and in other

organic solvents About 10,000 times thinner than a

human hair, but up to 18cm in length Possesses high mechanical strength.

WHAT IT IS USED FOR

In solar cells: A carbon nanotube complex can be

formed from carbon nanotubes and fullerenes.

The fullerenes would trap the electrons under sunlight.

The nanotubes would help to allow the electrons to flow, producing electricity as a solar cell

WHAT IT IS USED FOR

Paper batteries: Batteries engineered to use a paper-thin

sheet of cellulose with aligned carbon nanotubes

The nanotubes acts as electrodes, and allows the devices to conduct electricity.

It provides a long, steady power output compared to a conventional battery, as it functions both as a lithium-ion battery and a supercapacitor.

WHAT IT IS USED FOR

Bullet-proof, stab-proof clothings: With high mechanical strength, it might

be able to stop bullets or knife from penetrating the body totally.

However, the bullet’s kinetic energy might still cause broken bones and internal bleeding.

Hence, it is still a work in progress.

CARBON NANOTUBES (EXPLORATION) Carbon may have even more

applications in other fullerene structures. Nanotubes are only one of the fullerenes that have a tube shape.

Fullerenes also consist of spherical shapes, which are able to store electricity or heat.

In general, they have more unusual properties chemically, physically and biologically, as showed in the nanotubes too.

SILVER NANOPARTICLES (INTRODUCTION) Between 1 nm to 100 nm in size There are many routes to synthesizing

silver nanoparticles. Physical vapour deposition Ion implantation

The particles grow in the substrate with the bombardment of ions

Wet chemistry Reduction of a silver salt with a reducing agent

with a colloidal stabilizer

WHAT IT IS USED FOR

Medical devices: Surgical instruments Surgical masks Wound dressings Treatment of HIV-1

WHAT IT IS USED FOR

Others: Household appliances

Samsung has created a material called “Silver Nano”, including silver nanoparticles on the surfaces of household appliances.

The cathode in a silver-oxide battery

REFERENCES

Chang Qing, Sun. (2008, June 27). Nanogold chemistry. Retrieved (2010, June 10) from http://www.scitopics.com/Nanogold_chemistry.html

Lehigh University (2004, April 29). Nanogold Does Not Glitter, But Its Future Looks Bright. ScienceDaily. Retrieved (2010, June 10) from http://www.sciencedaily.com/releases/2004/04/040428062059.htm 

Luna Nanoworks (n.d.). Nanotechnology - carbon nanomaterials. Retrieved (2010, June 16) from http://www.lunananoworks.com/products/trimetaspheres.asp

REFERENCES:

Nanomaterials. Wikipedia. Retrieved (2010, June 10) from http://en.wikipedia.org/wiki/Nanomaterials

Colloidal Gold. Wikipedia. Retrieved (2010, June 10) from http://en.wikipedia.org/wiki/Colloidal_gold

Carbon Nanotube. Wikipedia. Retrieved (2010, June 16) from http://en.wikipedia.org/wiki/Carbon_nanotube

Silver nanoparticles. Wikipedia. Retrieved (2010, June 16) from http://en.wikipedia.org/wiki/Silver_nanoparticles

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