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Buxton & District U3A Science Discussion Group

GrapheneAnn Clark & Linda Estruch15 November 2013

What are we going to talk about?Introduction Basic chemistry Carbon from diamond to grapheneProperties and production Projected uses and time scales Questions (preferably simple)Buxton & DistrictScience Discussion

Buxton & DistrictScience DiscussionWhat are we going to talk aboutIntroduction Basic chemistry Carbon from diamond to grapheneProperties and production Projected uses and time scales Questions (preferably simple)Buxton & DistrictScience DiscussionCarbon

Buxton & DistrictScience DiscussionWhy is carbon so special?Catenation is 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 structuresBuxton & DistrictScience DiscussionSilicon based life

Allotropes of CarbonAllotropes 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, graphite and fullerenes are the three solid allotropes of the element carbon

Buxton & DistrictScience DiscussionAllotropes of CarbonDiamondGraphite

Buxton & DistrictScience DiscussionGraphite & DiamondUses?GraphiteLubricantPencil leadsElectrodes DiamondCutting toolJewelleryBuxton & DistrictScience DiscussionAllotropes of CarbonFullerene bucky ballsThe 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.

Buxton & DistrictScience Discussion Fullerenes & NanotubesBy changing the number of carbons the shape can alter

By leaving the ends open, tubes formBuxton & DistrictScience DiscussionProperties & Uses of FullerenesSuperconductivity 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 cellBuxton & DistrictScience DiscussionProperties & 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'.Buxton & DistrictScience DiscussionNanotube 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 wallsProperties & Uses of Nanotubes (2)Buxton & DistrictScience DiscussionGrapheneIt 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!

Graphene

Buxton & DistrictScience DiscussionGraphene

Buxton & DistrictScience DiscussionQuestions?Buxton & DistrictScience Discussion