The family of carbon nanotubes is large. There can be single walled carbon nanotubes (SWNTs), which are like a rolled up sheet of graphene - a monolayer of carbon bonded into a tubelike structure or they could be multiwalled carbon nanotubes, which have concentric layers of these graphene tubes. These carbon nanotubes can have large aspect ratios (length to width) or could be cut into ultra short carbon nanotubes. In fact, carbon nanotubes come in thousands of different molecular weights and isomers.

One of the most interesting characteristic of Carbon Nanotubes is how dependent the material properties are on small changes in structure. For example, small changes in the way that the carbon atoms align results in the difference between the SWNT being a metal or a semiconductor. This difference in the way the carbons align is called Chirality. Here is an easy way to demonstrate what chirality is. Take a transparency sheet with graphene's structure copied on it and connect two ends to form a cylinder. That is the model of one kind of carbon nanotube with the chiral index of (n, m) where n is the number of carbon atoms across the grid (at the center of each hexagonal structure on your transparency) and m would be zero since you havent moved down the matrix. If you want to make another kind of nanotube, you need to twist the graphene transparency and make a new tube that has a constant diameter. Scientists discovered an odd trend. When (n-m) is divisible by 3 (the product is an integer) then the SWNT is metallic, otherwise it is a semiconductor. Small changes in the arrangement of carbon atoms affects the electronic nature of these materials.
Make your own Carbon Nanotube by printing out this graphene sheet and trying different rollups.  Notice how the diameter changes.  

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Tags: chirality, k-12, nanotubes


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Publications by A. Paszternák:

Smartphone-Based Extension of the Curcumin/Cellophane pH Sensing Method

Pd/Ni Synergestic Activity for Hydrogen Oxidation Reaction in Alkaline Conditions

The potential use of cellophane test strips for the quick determination of food colours

pH and CO2 Sensing by Curcumin-Coloured Cellophane Test Strip

Polymeric Honeycombs Decorated by Nickel Nanoparticles

Directed Deposition of Nickel Nanoparticles Using Self-Assembled Organic Template,

Organometallic deposition of ultrasmooth nanoscale Ni film,

Zigzag-shaped nickel nanowires via organometallic template-free route

Surface analytical characterization of passive iron surface modified by alkyl-phosphonic acid layers

Atomic Force Microscopy Studies of Alkyl-Phosphonate SAMs on Mica

Amorphous iron formation due to low energy heavy ion implantation in evaporated 57Fe thin films

Surface modification of passive iron by alkylphosphonic acid layers

Formation and structure of alkylphosphonic acid layers on passive iron

Structure of the nonionic surfactant triethoxy monooctylether C8E3 adsorbed at the free water surface, as seen from surface tension measurements and Monte Carlo simulations

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