NANOMATERIALS COURSE

1. NANOMATERIALS COURSE HONOURS LECTURES 2008 LECTURER: DR. M. J. MOLOTO OFFICE: C204 Consultation Hours: 2 – 3, Mon – Fri OR by appointment Suggested Reading Materials: Nanochemistry: A chemical approach to nanomaterials by Geoffrey A. Ozin & Andre C. Arsenault Nanostructures and nanomaterials – synthesis, properties & applications by Guozhong Cao Principles of nanotechnology: molucular-based study of condensed matter in small systems by G. Ali Mansoori Further publications suggested in class

2. Assignment 1 • Choose one materials like CdS or Ag nanoparticles and use it to calculate the radius of the nanomaterial from the band edges. Find the equation in the texts or online. • Identify the material that you are not doing research and discuss the nature, chemistry and properties in nanoscale. • Submission date: • Duration: 1 Week.

3. ASSIGNMENT 2008 Choose from the four topics given and write at least three pages about the principle, properties and variation of size of particles of materials chosen. In relation to the size show a calculation that depicts the properties and size of particles. The four topics: (a) Carbon nanotubes (CNT), (b) Semiconductor nanoparticles (Quantum dots), (c) Thin Films and (d) Polymer Nanocomposites (PNC). Each student must choose a topic that is not current an area of their project title. Submission Date : Last week of lectures Week of 15 September 2008

4. HOW SMALL IS NANO • Nanotechnology deals with small structures or small-sized materials with dimensions from subnanometer to several hundred nanometers 1 nm = 10-9 m or 1 nm = a billionth of a metre 1 nm = 10-3 micrometer = 10 Å 1 m = 103 cm = 106 mm = 109 nm = 1010 Å 1 nm is equivalent to 10 H atoms or 5 Si atoms aligned in a line

6. Ethane C-C Bond 2 nm 1 nm Defining Nanoscale Science Nanoscale science can be defined as the chemistry and physics of structures that are on the length scale of 1-100 nm (1nm = 10-9 m or 10 Å), or require tolerances below 100 nm. http://www.nobel.se/chemistry/laureates/1996/index.html 1.543 Å or 0.1543 nm

7. C60 – Buckminsterfullerene 2 nm 1 nm A Gold Nanoparticle: about 300 Gold Atoms

8. Nano and Life Perspective Atom 0.1 nm DNA (width) 2 nm Protein 5 – 50 nm Virus 75 – 100 nm Materials internalized by cells < 100 nm Bacteria 1,000 – 10,000 nm White Blood Cell 10,000 nm

9. Biopharmaceutics Drug Delivery Drug Encapsulation Functional Drug Carriers Drug Discovery Implantable Materials Tissue Repair and Replacement Implant Coatings Tissue Regeneration Scaffolds Structural Implant Materials Bone Repair Bioresorbable Materials Smart Materials Implantable Devices Assessment and Treatment Devices Implantable Sensors Implantible Medical Devices Sensory Aids Retina Implants Cochlear Implants Surgical Aids Operating Tools Smart Instruments Surgical Robots Diagnostic Tools Genetic Testing Ultra-sensitive Labeling and Detection Technologies High Throughput Arrays and Multiple Analyses Imaging Nanoparticle Labels

10. Nanotechnology : • A technology of design, fabrication and applications of nanostructures and nanomaterials • Is concerned with materials and systems whose structures and components exhibit novel and significantly improved physical, chemical and biological properties, phenomena and processes due to their nanoscale size • Is a multidisciplinary field: chemists, physisits, material scientists, engineers, molecular biologists, pharmacologists etc.

11. Physical properties of nanomaterials • Nanomaterials may have a significantly lower melting point or phase transition temperature and appreciably reduced lattice constants, due to a huge fraction of surface atoms in the total amount of atoms • Mechanical properties of nanomaterials may reach the theoretical strength, which are one or two orders of magnitude higher than that of single crystals in the bulk form. The enhancement in mechanical strength is due to the reduced probability of defects. • Optical properties of nanomaterials can be significantly different from bulk crystals. E.g. The optical absorption peak of a semiconductor nanoparticle shifts to short wavelength, due to an increased band gap. The colour of metallic nanoparticles may change with their sizes due to surface plasmon resonance. • Electrical conductivity decreases with a reduced dimension due to increased surface scattering. However, electrical conductivity of nanomaterials could also be enhanced appreciably, due to the better ordering in microstructure, e.g. polymeric fibrils. • Magnetic properties of nanostructured materials are distinctively different from that of bulk materials. Ferromagnetism of bulk materials disappears and transfers to superparamagnetism in the nanometer scale due to the huge surface energy. • Self-purification is an intrinsic thermodynamic property of nanostructures and nanomaterials. Any heat treatment increases the diffusion of impurities, intrinsic structural defects and dislocations, and one can easily push them to the nearby surface. Increased perfection would have appreciable impact on the chemical and physical properties. For example, chemical stability would be enhanced. Properties of nanostructured materials are size dependant. Properties can be tuned simply by adjusting the size, shape or extent of agglomeration.

12. Properties of a material vary with the size of the material • (Bulk) Gold is a shiny yellow metal • Nanoscopic gold, i.e. clusters of gold atoms measuring 1 nm across, appears red • Bulk gold does not exhibit catalytic properties • Au nanocrystal is an excellent low temperature catalyst. • Therefore, if we can control the processes that make a nanoscopic material, then we can control the material’s properties. Therefore, if we can control the processes that make a nanoscopic material, then we can control the material’s properties.

14. Nanofabrication techniques: grouped according to the form of products • Nanoparticles: • colloidal processing • flame combustion • phase segregation • Nanorods or nanowires: • template-based electroplating • solution-liquid-solid growth (SLS) • Thin films: • Chemical vapour deposition (CBD and MOCVD) • Molecular beam epitaxy • Atomic layer deposition • Nanostructured bulk materials: • Photonic bandgap crystals by self-assembly of nanosized particles

15. INTRODUCTION • Nanoscale science is concerned with the creation of structures on the length scale of 1-100 nm. • There are two driving forces for nanoscale science: • (i) The top-down approach which is driven by the microelectronic industry. • (ii) The bottom-up approach which was initially driven by the curiosity of chemists to emulate natures large functioning biomolecules, but is increasingly being driven by a convergence with the top-down approach to make new nanoelectronic devices. • Thus, nanoscale science is more than creating structures on the length scale of 1-100 nm; it is about making nanostructures which also function in some way.

16. There are two approaches to making structures on the nanoscale, • The bottom-up approach: whereby structures are made atom-by-atom and molecule-by-molecule, harnessing covalent, ionic, metallic or non-covalent bonds. This approach represents how nature self-assembles functioning nanostructures, such as enzymes and viruses, or • The top-down approach: whereby structures are etched into bulk materials such as silicon. This approach represents how silicon chips are fabricated,

17. How Do We Make Things Small?Nanofabrication

18. How Do We Make Things Small?Nanofabrication Nanotechnology Lithographic Techniques Molecular Beam Epitaxy SPM Probes Supramolecular Chemistry – Aggregates Nanoparticle Synthesis CovalentChemistry – Dendrimers

19. A Few NANOMETRE Milestones 3.5 billion years ago The first living cells emerge. Cells house nanoscale biomachines that perform such tasks as manipulating genetic material and supplying energy. 400 B.C. Democritus coins the word "atom," which means "not cleavable" in ancient Greek. 1905 Albert Einstein publishes a paper that estimates the diameter of a sugar molecule as about one nanometer. 1931 Max Knoll and Ernst Ruska develop the electron microscope, which enables subnanometer imaging. 1959Richard Feynman gives his famed talk "There's Plenty of Room at the Bottom”, on the prospects for miniaturization. 1968Alfred Y. Cho and John Arthur of Bell Laboratories and their colleagues invent molecular-beam epitaxy, a technique that can deposit single atomic layers on a surface. 1974Norio Taniguchi conceives the word "nanotechnology" to signify machining with tolerances of less than a micron. 1981Gerd Binnig and Heinrich Rohrer create the scanning tunnelling microscope, which can image individual atoms.

20. A FewNANOMETRE Milestones • 1985 Robert F. Curl, Jr., Harold W. Kroto and Richard E. Smalley discover buckminsterfullerenes, also known as buckyballs, which measure about a nanometer in diameter. • 1986 K. Eric Drexler publishes Engines of Creation, a futuristic book that popularizes nanotechnology. • 1989Donald M. Eigler of IBM writes the letters of his company's name using individual xenon atoms. • 1991 Sumio Iijima of NEC in Tsukuba, Japan, discovers carbon nanotubes. • 1993 Warren Robinett of the University of North Carolina and R. Stanley Williams of the University of California at Los Angeles devise a virtual-reality system connected to a scanning tunneling microscope that lets the user see and touch atoms. • 1998 Cees Dekker's group at the Delft University of Technology in the Netherlands creates a transistor from a carbon nanotube. • 1999James M. Tour, now at Rice University, and Mark A. Reed of Yale University demonstrate that single molecules can act as molecular switches. • 2000 The Clinton administration announces the National Nanotechnology Initiative, which provides a big boost in funding and gives the field greater visibility. • 2000 Eigler and other researchers devise a quantum mirage. Placing a magnetic atom at one focus of an elliptical ring of atoms creates a mirage of the same atom at another focus, a possible means of transmitting information without wires.

21. 2 nm 1 nm C60 – Buckminsterfullerene Richard E. Smalley Sir Harold W. Kroto Robert F. Curl Jr.

22. 1959: Richard P. Feynman; Plenty of room at the bottom • As soon as I mention this, people tell me about miniaturization, and how far it has progressed today. They tell me about electric motors that are the size of the nail on your small finger. And there is a device on the market, they tell me, by which you can write the Lord's Prayer on the head of a pin. But that's nothing; that's the most primitive, halting step in the direction I intend to discuss. It is a staggeringly small world that is below. In the year 2000, when they look back at this age, they will wonder why it was not until the year 1960 that anybody began seriously to move in this direction. Why cannot we write the entire 24 volumes of the Encyclopedia Brittanica on the head of a pin? He discussed a "great future" in which "we can arrange the atoms the way we want." Feynman's "great future" arrived in 1989 with the discovery of ways to manipulate atoms with the Scanning Tunneling Microscope.

23. Nanocare revolutionizes fabric technology Nano-CareTM fabrics sold since Nov. 2001, incorporate “nano-whiskers” into the fabric to makeit stain-resistant to water-based liquids such as coffee and wine. • This Lee Performance Khaki Pant features Nanocare fabric • Product Features: * Nanocare fabric repels liquids* • Wrinkle free Lee Nanocare khaki pant fabric * Stain resistant

24. AUSSIES BASK IN THE SUMMER SUN, NANOPOWDERS PROTECTING THEIR SKIN By Debbi Gardiner Small Times Correspondent  Jan. 7, 2003 • Various sunscreens (Wild Child, Wet Dreams and Bare Zone) incorporate ZinClearTM, a transparent suspension of nanoscopic zinc oxide particles that are too small to scatter visible light as do products containing microscopic particles. • ZinClear allows UV protection without the funny "chalky" look conventional sunscreens give. It's made with an APT-patented method of processing high quality nanopowders. • “Zinc oxide is a natural UV filter but its marketability was lacking because of its whiteness. Now we can make it transparent,” said Brian Innes, business development manager at APT.

25. Nanomaterials in action… • Wilson Double CoreTM tennis ball has clay nanoparticles embedded in the polymer lining of its inner wall, which slows the escape of air from the ball making it last twice as long.

26. Carbon nanotube stabilizers in Tennis rackets increase torque and flex resistance