1. Chemical Bonding of Carbon Nanotubes
Doug Wylie 04/20/04

2. 2 Types of Bonding related to Nanotubes
Covalent Bonding – Strong bond between individual neighbouring carbon atoms in a single tube
Bonding found along the 2-D plane in a hexagonally close packed sheet of graphite
Van der Waal Forces – Weak bond between the individual nanotubes themselves
Bonding between separate layers of graphite
(Reason why graphite is an excellent lubricant, and why talcum powder feel so smooth!)

3. Nanotubes are composed entirely of sp2 bonds, similar to graphite
Nanotubes are composed entirely of sp2 bonds, similar to graphite. Stronger than the sp3 bonds found in diamond. This bonding structure provides them with their unique strength.
Nanotubes naturally align themselves into "ropes" held together by Van Der Waal Force.
Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, giving great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking.

5. Typical Values of a Single Walled Carbon Nanotube
Equilibrium Structure
Average Diameter of SWNT's nm
Distance from opposite Carbon Atoms Å
Analogous Carbon Atom Separation Å
Parallel Carbon Bond Separation Å
Carbon Bond Length Å
C - C Tight Bonding Overlap Energy ~ 2.5 eV
Lattice Constant Å

6. Comparison between Diamond and Graphite

7. Comparison showing Diamond and Graphite bonding along the cube body-diagonal direction ie: perpendicular to the planes of packing

8. Conclusions
Covalent bonding is a very strong bond (can often be stronger than Ionic bonding)
Weak VdW forces allow rolling up of indivitual graphite sheets into tubes.
Electrons are shared between Carbon atoms so as to fill outer electron shells.
Covalent bonds are highly directional (unlike Ionic) therefore only a few characteristic shapes are found.
Carbon Nanotubes exhibit quite different properties related to size and width of tube but the bonding type remains the same.