Transcript Slide 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
Assignment 1
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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.
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
HOW SMALL IS NANO
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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
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
Ethane C-C Bond
1 nm
1.543 Å
or
0.1543 nm
2 nm
1 nm
2 nm
C60 – Buckminsterfullerene
A Gold Nanoparticle:
about 300 Gold Atoms
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
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
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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.
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Physical properties of nanomaterials
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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.
Properties of a material vary with the
size of the material
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(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.
Nanofabrication techniques: grouped
according to the form of products
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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
INTRODUCTION
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Nanoscale science is concerned with the creation of structures
on the length scale of 1-100 nm.
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There are two driving forces for nanoscale science:
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(i) The top-down approach which is driven by the
microelectronic industry.
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(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.
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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.
There are two approaches to making
structures on the nanoscale,
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The bottom-up approach: whereby structures
are made atom-by-atom and molecule-bymolecule, 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,
How Do We Make Things Small?
Nanofabrication
How Do We Make Things Small?
Nanofabrication
Biological
World
Non-Biological
World
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Top
Nature
Physics
nm
Structure
leads to
Function
Molecular Beam Epitaxy
SPM Probes
Down
Nanotechnology
Chemistry
Up
Å
Lithographic Techniques
Bottom
Supramolecular Chemistry – Aggregates
Nanoparticle Synthesis
Covalent Chemistry – Dendrimers
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.
1959 Richard Feynman gives his famed talk "There's Plenty of Room at
the Bottom”, on the prospects for miniaturization.
1968 Alfred 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.
1974 Norio Taniguchi conceives the word "nanotechnology" to signify
machining with tolerances of less than a micron.
1981 Gerd Binnig and Heinrich Rohrer create the scanning tunnelling
microscope, which can image individual atoms.
A Few NANOMETRE Milestones
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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.
1989 Donald 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 virtualreality 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.
1999 James 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.
The Nobel Prize in Chemistry 1996
O
1 nm
2 nm
H
H
N
"for their discovery of fullerenes"
C60 – Buckminsterfullerene
Robert F. Curl Jr.
Sir Harold W. Kroto
Richard E. Smalley
OH
1959: Richard P. Feynman;
Plenty of room at the bottom
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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.
Nanocare revolutionizes fabric
technology
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This Lee Performance Khaki Pant features
Nanocare fabric
Product Features: * Nanocare fabric
repels liquids*
Wrinkle free Lee Nanocare khaki pant
fabric * Stain resistant
Nano-CareTM fabrics sold since Nov. 2001, incorporate “nanowhiskers” into the fabric to make
it stain-resistant to water-based liquids such as coffee and wine.
AUSSIES BASK IN THE SUMMER SUN, NANOPOWDERS
PROTECTING THEIR SKIN By Debbi Gardiner
Small Times Correspondent
Jan. 7, 2003
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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.
Nanomaterials in action…
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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.
Carbon nanotube stabilizers in Tennis rackets
increase torque and flex resistance