Buxton & District U3A Science Discussion Group “ Graphene ”

1. Buxton & District U3A Science Discussion Group“Graphene” Ann Clark & Linda Estruch15 November 2013

2. What are we going to talk about? • Introduction • Basic chemistry – Carbon from diamond to graphene • Properties and production • Projected uses and time scales • Questions (preferably simple)

4. What are we going to talk about • Introduction • Basic chemistry – Carbon from diamond to graphene • Properties and production • Projected uses and time scales • Questions (preferably simple)

5. Carbon

6. Why is carbon so special? • Catenationis the linkage of atoms of the same element into longer chains. Catenation occurs most readily in carbon, which forms bonds with other carbon atoms to form longer chains and structures

7. Silicon based life

8. Allotropes of Carbon Allotropes are different forms of the same element in the same physical state (solid, liquid, gas). They occur due to different bonding arrangements and so diamond, graphiteand fullerenesare the three solid allotropes of the element carbon

9. Allotropes of Carbon • Diamond • Graphite

10. Graphite & Diamond Uses? Graphite • Lubricant • Pencil leads • Electrodes Diamond • Cutting tool • Jewellery

11. Allotropes of Carbon Fullerene – ‘bucky balls’ The name Buckminsterfullerene (fullerene-60), is derived from the American architect R. Buckminster Fuller who invented the geodesic dome design in building construction. Soot and charcoal are not allotropes they are amorphous carbon mainly impure graphite in structure.

12. Fullerenes & Nanotubes By changing the number of carbons the shape can alter By leaving the ends open, tubes form

13. Properties & Uses of Fullerenes • Superconductivity and ferromagnetism • C60 is an optical limiter. • When light is shone on it, solution of fullerene-60 instantly turns darker • the more intense the light, the darker it gets, • so the intensity of transmitted light is limited to a maximum value. • This limiting light transmittance property can be used in the design of safety goggles in intense light situations e.g. people working with laser beams • May be used as vehicles to carry drugs into cells, • the cage like fullerene molecules could contain a drug, • the combination can pass easily through the wall of a target cell

14. Properties & Uses of Nanotubes (1) • Some nanotubes are excellent insulators, semiconductors or conduct electricity as well as copper! • can be used as semiconductors or 'miniature wires’. • of great use in miniature electronic circuitry in computers and other electronic devices • They act as a component of industrial catalysts • The catalyst can be attached to the nanotubes which have a huge surface are per mass of catalyst 'bed'.

15. Properties & Uses of Nanotubes (2) • Nanotube fibres are very strong and so they are used in 'composite materials' e.g. reinforcing graphite in carbon fibre tennis rackets. • Bundles of the nanotubes, processed into fibres, have very high tensile strength and can be stronger than steel with only 1/6th the weight. • Nanotubes can 'cage' other molecules and can be used as a means of delivering drugs in controlled way to the body because the thin carbon nanotubes can penetrate cell walls

16. Graphene Graphene • It is possible to synthesise graphite in individual layers just one atom thick and the product is known as graphene. It has a 'honeycombed' lattice. • Technically graphene is a fourth allotrope of carbon although it is just a single layer of graphite!

17. Graphene

18. Questions?