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An introduction to nanoscience and nanotechnology

An introduction to nanoscience and nanotechnology 24
An introduction to nanoscience and nanotechnology Questions to consider • What is a nanoparticle • How big is ‘nano’ • How big is a nanometre • What is a nanoscience • Why nano • What is a nanotechnology • What opportunities are hidden in the nanodimension • What techniques are there for characterising nanoparticles What is a nanoparticle Chemical composition •metals/metal oxides •polymers, carbon •semiconductors Origin •biomolecules •natural •compounds . . . •unintentionally released •manufactured Nanocapsules Quantum Ultrafine Dots Shape/structure Aerosols Dispersed in •spheres •gases (aerosols) Nanoparticulate •needles •liquids (e.g. gels, ferrofluids) Materials •platelets •solids (matrix materials) Nanoparticles •tubes Nanotubes Aggregation state •single particles Surface modification •aggregates •Untreated (as obtained in production process) •agglomerates •Coated (e.g. conjugates, polymer films) •Core/shell particles (e.g. spheres, capsules) What is a nanoparticle An example is a bucky ball – a fullerene 1 nm – 60 carbon atoms linked together in one unit. How big is ‘nano’ ratio ratio earth / football = football / fullerene © Dan Marsh © Paul W. Brian How big is a nanometre It is a million times smaller than the smallest measurement you can see on a ruler It is a millionth of a millimetre or a billionth of a metre A man’s beard grows A human fingernail grows 5 nanometres every second. 1 nanometre every second. This is a silver nanowire resting on a human hair. Look at a strand of your own hair and imagine how small that is… What is nanoscience The study and manipulation of materials at the nanoscale Why nano At the nanoscale, strange things happen to materials – their properties can change. Reactivity As particles get smaller they tend to react differently with their environment than larger particles. Size Smaller particles can have different optical properties: their colours change because different sizes of particle reflect and absorb light differently. Magnetism Smaller particles can have different magnetic properties than larger. Reactivity Necessary understanding: • What an atom, a molecule, a nanoparticle and a chemical reaction is. • How the surface of a cube is calculated. • How the volume of a cube is calculated. Example: Which dissolves faster in water granulated sugar sugar cubes Size Which of these is Gold The colour of gold can range from purple to red depending on the size of the atom clusters. Different sizes of particles reflect and absorb light differently. Hundreds of years ago it was known as art Red stained glass gets its colour from nanoparticles of gold that are only 20 nanometres across. Orange glass gets its colour from gold Now we call it nanoparticles that are 80 nanometres across. nanotechnology What is Nanotechnology The development of materials and devices by exploiting the characteristics of particles on the nanoscale (by humans). Potential impacts of nanotechnology Health: Diagnostics, Cancer treatment and targeted drug delivery. Potential impacts of nanotechnology Materials: Sports industry, cosmetics, clothing and space elevators. Potential impacts of nanotechnology Technology: Faster processing, morphing computers and smaller, more powerful mobile devices. Potential impacts of nanotechnology Environment Cleaner energy, better energy storage and treatment of water. How do we build small things Computer chips can be made “Topdown”– building something by starting with a larger component and carving away material (e.g. like a sculpture). Metal nanowires are made “Bottomup”– building something by assembling smaller components (e.g. like building a car engine or Lego). It’s a question of size . . . . macro, micro and nano What we want to see dictates what instruments we use: Beyond the magnifying glass • Optical microscopes • Electron microscopes • Surface analysis • Elemental analysis • and more……. Beyond the magnifying glass Which can be modelled and demonstrated in R class with Lego Atomic Force Microscope Techniques for measuring the size of nanoparticles AFM/STM etc Sieves Electron microscopy Optical microscopy Sedimentation Disc centrifuge Electrozone sensing PCS (Dynamic Light Scattering) Laser diffraction Acoustic spectroscopy 0.001 0.01 0.1 1.0 10 100 1000 10000 Size (microns) 1 nanometre Compared with the number of techniques for measuring the size of a particle greater than 1 micron, there are very few techniques that are able to accurately measure the size of small particles, particularly those less than 10 nanometres. Nano Teachers’ Day Experimental sessions: • Session 1: What is nano • Session 2: Carbon nanotubes and buckyballs. • Session 3: Colourful nanoworld – making gold and silver nanoparticles. • Session 4: Make your own solar cells. Session 1: These activities are aimed at finding ways of experiencing the nano world and gaining confidence in using numbers to explain what we can’t see. Nano is natural as well as manufactured. Session 2: Carbon nanotubes and buckyballs. Nanotubes are extended Bucky balls. They can be natural and manufactured. This activity shows bonding and crystal structure. The curved ends of the nanotube contain pentagons, the walls are the normal hexagonal structure. Session 3: Colourful nanoworld – making gold and silver nanoparticles. Left to right Tyndall effect gold, silver, plain water In Blue Peter fashion this works for y5 to y13. Session 4: Make and test your own solar cells. Any Questions
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