Question

Carbon has two main categories of allotropes – crystalline & amorphous. Among crystalline allotropic forms of carbon, diamond & graphite are known since long while the third category of carbon called the carbon nanotubes was is discovered around 1991. 

Now answer the questions : 

(i) What are carbon nanotubes ? In what respects their structures differ from buckminster fullerence ? 

(ii) What properties have made them so interesting? 

(iii) Name same applications which are envisioned for these interesting molecules.  

Answer 1

(i) A carbon nanotube consists of a two-dimensional array of hexagonal rings of carbon just as in a layer of graphite or a chicken wire. The layer (or the chicken wire) is then rolled into a cylinder and capped at each end with half of a C60- fullerene. 

(ii) Carbon nanotubes are very tough, about 100 times as strong as steel. They are electrically conducting only along the length of the tube. 

(iii) Carbon nanotubes can be used to produce very strong composite materials. They are also being used as probe tips for analysis of DNA and proteins by atomic force microscopy (AFM). It is also thought that carbon nanotubes ca be used to make molecular size test tubes or capsules for rug delivery.