Properties Of NanoMaterials..!

[Nethra K Putti]

PROPERTIES OF NANOMATERIALS

4 PROPERTIES OF NANOMATERIAL:

1. Carbon Nanotubes :
carbon nanotubes were first observed by sumio Iijima in 1991. CNT's are extended tubes of rolled graphene sheets. there are two types of CNT's:a) single-walled b) multi-walled. both of these are typically a few nanometers in diameter and several micrometers (10-6m) to centimeters long. CNT's have assumed an important role in the context of nanomaterials, because of their novel chemical and physical properties.

- they are mechanically very strong (their Young's modulus is over 1 terapascal, making CNT's as stiff as diamond), flexible(about their axis), and can conduct electrically extremely well the helicity of the graphene sheet determines whether the CNT is a semiconductor or metallic. all of these remarkable properties give CNT's a range of potential applications .
Ex: in reinforced composites, sensors, disply devices etc.

2. Fullerenes (carbon 60):
in the mid-1980s a new class of carbon material was discovered called carbon 60. these are spherical molecules about 1nm in diameter, comprising 60 carbon atoms arranged as 20 hexagons and 12 pentagons. the C60 species was named 'Buckminsterfullerene' in recognition of the architect buckminster fuller, who was well-known for building geodesic domes, and the term fullerenes was then given to any closed carbon cage. in 1990, a technique to produce larger quantities of C60 was developed by resistively heating graphite rods in a helium atmosphere. several application are envisaged for fullerenes, such as miniature 'ball bearings' to lubricate surfaces, drug delivery vehicles & in electronic circuits.

3. Dendrimers :
dendrimers are spherical polymeric molecules, formed through a nanoscale, hierarchical self-assembly process. there are many types of dendrimers; the smallest is several nanometers in size. dendrimers are used in conventional applications such as coatings and inks , but they also have a range of interesting properties which could lead to useful applications.

4. Quantum Dots :
nanoparticals of semiconductors (quantum dots) were theorized in the 1970s. and initially created in early 1980s. if semiconductors particles are made small enough, quantum effects come into play, which limit the energies at which electrons and holes (the absence of an electron) can exist in the particles. as energy is related to wavelength , this means that the optical properties of the particles can be speciifc wavelengths (colors) of light, merely by controlling their size. recently, quantum dots have found applications in composites, solar cells (gratzel cells) anf flurocent biological labels which are used for both the small particle size and tuneable energy levels. recent advances in chemistry have resulted in the preparation of monolayer-protected, high-quality, monodispersed, crystalline quantum dots as small as 2nm in diameter,which can be conveniently treated and processed as a typical chemcial reagent.

[kitty15]

Hello Friends......

Nanomaterial is a field that takes a material science based approach to nanotechnology.It studies materials with morphological features on the nanoscale , and especially those that have special properties stemming from their nanoscale dimensions. Nanoscale is usually defined as smaller than a one tenth of a micrometer in at least one dimension,though this term is sometimes also used for materials smaller than one micrometer.

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