Introduction to Nanotechnology PDF

Faculty of Biotechnology General Chemistry Chapter 10 Introduction to nanotechnology Dr. M. Abd-Elhakeem This slide is adapted from the lecture notes posted at http://www.nanohub.org/courses/nanomaterials by Prof. Mark Hersam  What is Nanotechnology? The design, characterization and applic...

Faculty of Biotechnology General Chemistry Chapter 10 Introduction to nanotechnology Dr. M. Abd-Elhakeem This slide is adapted from the lecture notes posted at http://www.nanohub.org/courses/nanomaterials by Prof. Mark Hersam  What is Nanotechnology? The design, characterization and application of materials, devices and systems that have nanometer dimension A nanometre (nm) is The word ‘nano’ comes 0.000 000 001 metre (or 10-9 m). That’s from the Greek word one millionth of a millimetre. which means ‘dwarf’. Nanoparticles are very small, less than 100 nm across, but just how small is that? A red blood cell is 7,000 nm wide and a water molecule is 0.3nm across. Soccer: 22cm Carbon 60: 0.7nm Carbon Tube: 1.4nm Pet Flea: 1mm Hair: 80mm Red Cell: 7mm Virus: 150nm DNA: 2nm TiOx Particles: 13nm IBM Logo: 5nm  Compared to Human Hair A Human Hair is about 100,000µm wide  Nanoparticles A particle is defined as a small object that behaves as a whole unit with respect to its transport and properties. Fine particles are sized between 100 and 2,500 nanometers Coarse particles cover a range between 2,500 and 10,000 nanometers.  A nanoparticle is Particle of any shape with dimensions in the 10- 100nm range. Nanoparticles are bridge between bulk materials and atomic or molecular structures  The basis of the 100-nm limit is the fact that novel properties that differentiate particles from the bulk material typically develop at a critical length scale of under 100 nm. occasionally the use of the prefix nano is accepted for dimensions smaller than 500 nm.  Properties of nanoparticles I. Nanoparticles have a much bigger surface area to volume ratio than larger particles. Single Box Ratio 6 m2 = 6 m2/m3 1m 3 Smaller Boxes Ratio 12 m2 = 12 m2/m3 1m 3 1 2 This fact may be applied in all field utilize the metal surface to be Lighter Stronger Faster Smaller More Durable II. Nanoparticles have more atoms or molecules nearer the surface than larger particles. Materials reduced to the nanoscale can show different properties compared to what they exhibit on a macroscale, enabling unique applications  1. Color Nanoparticles often possess unexpected optical properties as they are small enough to confine their electrons. For example, gold nanoparticles appear deep- red to black in solution. Nanoparticles of yellow gold and grey silicon are red in color. Nanoparticles also interact differently with light. Normally, gold metal appears gold in colour. However, nanoparticles of gold in solution appear red and blue in colour. Different-sized nanoparticles of gold give different coloured solutions. Smaller nanoparticles appear red in solution, while slightly larger nanoparticles appear blue  2. Formation of suspensions Suspensions of nanoparticles are possible since the interaction of the particle surface with the solvent is strong enough to overcome density differences, which otherwise usually result in a material either sinking or floating in a liquid. History of Nanotechnology  Natural nanoparticles  lizards are able to stick to walls because of the nanostructures on their feet.  Spiders’ webs are made of super-strong nanofibres.  Butterflies’ wings contain shiny reflective nanocrystals. Nanotechnology scientists try to copy natural nanoparticles to make new materials that are useful. History of Nanotechnology – First Example The “Lycurgus Cup” is a Roman artifact from before 640 AD. It is dichroic, changing colour when illuminated from the inside. This effect is caused by gold History of Nanotechnology – Stained Glass As early as 500 AD, glass artisans were making stained glass windows with vibrant reds and yellows. These colours were much more luminous and durable than dyes could produce. They were the products of “coinage metal” nanoparticles imbedded in the glass. 22 History of Nanotechnology – Coinage Metals As these nanoparticles get smaller, the colours shift from red, through yellow and green, to blue. Here is an example of a copper nanocrystal that is roughly 100 nm across. 23 History of Nanotechnology - Photography In 1827, Joeph Niépse was able to stabilise silver halide nanocrystals in a gelatin that hardened with exposure to light. The silver halides decomposed to silver metal, producing black. The crystal grains were too small to be discerned, and so black-and-white photography gave excellently resolved photos. 24 History of Nanotechnology - Colloids Nanoparticles “stay in solution”, leading to one of the most enduring images of nanotechnology: The rainbow array of solutions made by the suspension of a variety of sizes of nanoparticles. This was discovered by Michael Faraday in 1857. 25 The idea of nanotechnology was suggested in 1959 by Richard Feynman, an American physicist. Scientists have since made structures smaller and smaller. This work is now called nanotechnology, a term first used in 1974 by Norio Taniguchi, a materials scientist in Japan. As scientists have steadily made things smaller, they have needed new pieces of equipment to help them. In 1981, the scanning tunnelling microscope (STM) was invented and allowed scientists to see the nano-world. Scanning probe microscope systems from Scanning tunneling microscope image. nanoscience instruments. Using an STM, it is possible to see individual atoms and even move them around. In 1989, an STM was used to move 35 xenon atoms onto a tiny piece of nickel. The element carbon can exist in different structural forms, which are known as allotropes. Diamond and graphite are the two most common allotropes of carbon. Carbon can also exist in other forms, collectively called fullerenes. The first of these, buckminsterfullerene, was discovered by accident, in 1985, and its discovery opened up a whole new area of chemistry. The early 2000s saw the beginnings of commercial applications of nanotechnology, Which one are actual nano-products? This slide is adapted from the presentation on “An Introduction to Nanotechnology,” by Terry Bigioni, posted at http://www.homepages.utoledo.edu/tbigion/BigioniGroup/Outreach_Home.html  e! ar ey th r e H e This slide is adapted from the presentation on “An Introduction to Nanotechnology,” by Terry Bigioni, posted at http://www.homepages.utoledo.edu/tbigion/BigioniGroup/Outreach_Home.html  Nano-products Nano SilverSeal Refrigerator Display Screens Samsung (nanoparticle-coated) Quantum dots Nano-Products on the Market Now This slide is adapted from the presentation posted at www.toxicology.org/isot/rc/allegheny/Savage2006SOTRegional.ppt Modern Nanotechnology - Microelectronics The Xbox 360 is one of the most prevalent microelectronic technologies to employ nanotechnology. The method is “silicon-on-oxide”, which makes 100 nm silicon layers. This allows for a decrease in microelectronic device size, and so an increased density within a chip. 34 Modern Nanotech - Sunblock Zinc oxide and titanium oxide are both employed as opaque sunblocks. When particles are nanoscale, they become invisible to the human eye, but still reflect UV light. Modern sunblocks can provide a physical barrier without this classic appearance. 35 Modern Nanotechnology – Antimicrobial Fabric Nanohorizons, a company in the Pennsylvania, has started producing a silver nanoparticles The silver nanoparticles are toxic to microbes, and so colonies will never form, and clothes using this material will not have odors. 36 Future Directions - Solar Panels Newer solar panels now incorporate “nanocrystalline silicon”. This increases efficiency by “bouncing” the light around. Tiny machines in your body curing cancer? Synthesis of nanoparticles 2 general Protocols - bottom up approach - top down approach  BOTTOM UP APPROACH  Theseseek to arrange smaller components into more complex assemblies  Use chemical or physical forces operating at the nanoscale to assemble basic units into larger structures  TOP DOWN APPROACH These seek to create smaller devices by using larger ones to direct their assembly  The synthesis of nanoparticles includes 1. Physical methods: Nanoparticles are obtained via break down of large particles by any methods. Ex. Ball milling  2. Chemical methods: Metal salts are reacted with a reducing agent to precipitate the metal in nanosize by controlling reaction conditions  Synthesis of gold nanoparticles  Reduction of some metal salt or acid  Highly stable gold particles can be obtained by reducing chloroauric acid (HAuCl₄)with tri sodium citrate(Na₃C₆H₅O₇) HAuCl₄+ Na₃C₆H₅O₇ Au + C₆H₅O₇⁻+ HCl+3 NaCl In a similar manner, silver, copper and other metal nanoparticles can be synthesized.  Reaction conditions 1. Ultra diluted solution 2. High speed agitation 3. Dropwise addition of precipitating agent.  3. Biological methods Nanoparticles may be formed inside the bacterial cells Or Formed by action of extracellular enzymes Hyperthermia for treating cancer Hyperthermia is a biological term used to describe the phenomenon that occurs when living cells or tissues are heated to temperatures slightly above the highest that can occur naturally The END of the Course