2. Introduction
NanoParticles: are the particles having the size
ranging from 1-50 nm.
·Generally they are obtained from colloids.
·They possess good electrical, magnetic and optical
properties.
·Nanoparticle exhibit electronic property governed by
quantum physics, they are called quantum dots.
3. Basics of Nanochemistry
• Nanomaterial Possess size less than
100nm atleast in one dimension
• Nanomaterial in One dimension – are
layers such as thin film or surface coating
• Nanomaterial in two dimension are tubes
such as Nanotubes and Nano wire
• Nanomaterial in three dimension are
Particles like precipitates, colloids and
quantum dots.
4. Nanochemistry (or) Nanoscience
Nanoscience is defined as the study of
phenomena and manipulation of materials at
atomic, molecular and macromolecular
scales.
Nanotechnology
Nanotechnology as the design of structures,
systems, devices by controlling the size and
shape at 10-9
m scale
5. Comparison of atoms/molecule,nano
particles/ cluster,bulk materials
S.
No.
Property Atoms/Molecules Nano Materials Bulk Materials
1
Size of the
Particle
Few Angstroms (A)
Angstrons to Nano meter
(10-10
m – 10-9
m)
Migons to higher
(10-6
m to higher)
2
Number of
Constituent
Particles
One atom to few
many atoms
Few atoms to several
thousands of atoms
Infinite
3
Electronic
structure
Confired Confired
Not confired
(Continous)
6. 6 Random motion Present present (browi on) Not present
7 Stability Stable
Stable or unstable
depending on surface
energy
Stable
Example Nacl, Kcl, Fullence CNT
Gold Bar, Silver
Bar
7. Distinction between Nanoparticles
molecules and bulk materials
• The size of nano particles are less than
100nm in diameter,molecules are in the
range of picometers,but bulk materials are
large in micron size.
• Molecule is a collection of atoms, nano
particles are collection of few molecules
that is less than 100nm but bulk materials
contains thousand of molecules.
• Surface area of nano particles is more than
the bulk materials.
8. • Hardness of nano materials is 5 times
more than the bulk materials.
• Strength of nano materials is 3-10 times
higher than the bulk materials.
• Nano particles possesses size dependent
properties, but bulk materials possess
constant physical properties.
• Corrosion resistance is more than the bulk
materials hence localized corrosion in
nano materials is stopped.
9. • Behavior of bulk material can be changed
but cannot enter inside the nano particles.
• Nano particles due to its size possess
unexpected optical properties.
• Nano particles possesses lower melting
point than the bulk materials.
• Electrical properties resistivity of nano
particles are increased by 3 times.
• The wear resistance of nano particles are
170 times higher than the bulk materials.
10. Size Dependent Properties
• On a Nano Scale, Materials behave very differently when
compared to larger scales.
• Physical and chemical properties of a Nano material become
size-dependent
• Some of the major size dependent properties are
• Thermal Properties – Melting Temp
• Optical Properties- Absorption and scattering of light
• Chemical properties – Reactivity, catalysts
• Mechanical Properties – Mechanical strength
• Electronic Properties – Conductance behavior
• Magnetic Properties – Super Paramagnetic effect.
11. • Thermal Properties:
Nano crystal size decreases – Surface energy increases –
melting point decreases
• Optical properties : (Absorption and scateering of light)
• Mechanical Properties: increased hardness and toughness of
metals and alloy
• Electrical Properties: Increased electrical conductivity in
ceramics and magnetic nano composites. Electrical property
resistivity of nano material are increased by three times.
• Catalytic properties: better catalytic efficiency due to higher
surface to volume rates.
12. PREPARATION OF
NANOMATERIALS
The following two approaches are used for the synthesis of
nanomaterials.
1. Top-down process (or) Physical (or) Hard methods.
2. Bottom-up process (or) Chemical (or) Soft methods.
•Top-down process
Top-down process involves the conversion of bulk materials into
smaller particles of nano-scale structure
13. • Bottom-up process
Bottom-up process involves building-up of
materials from the bottom by atom by atoms,
molecule by molecule or cluster to the
nanomaterials.
14. Laser ablation
• In laser ablation technique, high-power laser pulse is used to
evaporate the material from the target. The stoichiometry of
the material is protected in the interaction.
• The total mass ablated from the target per laser pulse is
referred to as. the ablation rate
15. • This method involves vapourisation of
target material containing small amount of
catalyst (nickel or cobalt) by passing an
intense pulsed laser beam at a higher
temperature to about 120°C in a quartz
tube reactor. Simultaneously, an inert gas
such as argon, helium is allowed to pass
into the reactor to sweep the evaporated
particles from the furnace to the colder
collector.
16. Uses
1.Nanotubes having a diameter of 10 to 20 nm
and 100 μm can be produced by this method.
2.Ceramic particles and coating can be
produced.
3. Other materials like silicon, carbon can also
be converted into nanoparticles by this
method.
17. Advantages of laser ablation.
1. It is very easy to operate.
2. The amount of heat required is less.
3. It is eco-friendly method because no
solvent is used.
4.The product, obtained by this method, is
stable.
5. This process is economical.
18. Chemical Vapour Deposition
(CVD)
• This process involves conversion of
gaseous molecules into solid
nanomaterials in the form of tubes, wires
or thin films. First the solid materials are
converted into gaseous molecules and
then deposited as nanomaterials.
• Example: CNT preparation.
19. • The CVD reactor consists of a higher
temperature vacuum furnace maintained
at inert atmosphere. The solid substrate
containing catalyst like nickel, cobalt, iron
supported on a substrate material like,
silica, quarts is kept inside the furnace.
The hydrocarbons such as ethylene,
acetylene and nitrogen cylinders are
connected to the furnace. Carbon atoms
21. produced by the decomposition at 1000°C,
condense on the cooler surface of the
catalyst.
As this process is continuous, CNT is
produced continuously.
22. Types of CVD Reactor
Generally the CVD reactors are of two types
23. Hot-wall CVD
•Hot wall CVD reactors are usually tubular in
form. Heating is done by surrounding the
reactor with resistance elements.
Cold-wall CVD
•In cold-wall CVD reactors, substrates are
directly heated inductively while chamber
walls are air (or) water cooled.
24. Advantages of CVD
1. Nanomaterials, produced by this method, are
highly pure.
2. It is economical.
3. Nanomaterials, produced by this method, are
defect free.
4. As it is simple experiment, mass production in
industry can be done without major difficulties.
25. SYNTHESIS OF CARBON
NANOTUBES
Carbon Nano tubes can be synthesized by
any one of the following methods
•Pyrolysis of Hydrocarbons.
•Carbon arc method
•Laser evaporation
•Chemical vapour deposition
26. PYROLYSIS
• Carbon nanotubes are synthesized
by the pyrolysis of hydrocarbon
such as acetylene at about 700ºC
in presence of Fe-silica or Fe-
graphite as catalyst under inert
condition
27. CARBON ARC METHOD
• It is carried out by applying
direct (Current 60-100 A and
20-25V) Between graphite
electrodes of 10-20 um
diameter
28. Sol-Gel process
• The sol-gel process is a wet chemical
technique also known as chemical solution
deposition. It is the method for producing
solid materials from small molecules. This
method is used for the fabrication of metal
oxides. It involves conversion of monomers
into a colloidal solution (sol), that acts as
the precursor. This colloidal solution
gradually evolves towards the formation of
a gel-like system.
29. It involves the following steps.
1. Hydrolysis and polycondensation
2. Gelation
3. Aging
4. Drying
5. Densification
6. Crystallization
The volume fraction of particles (particle density)
may be slow that a significant amount of fluid
need to be removed for the gel-like properties to
be recognized. It is done by two ways.
30. (i) Sedimentation
•The solution is allowed to keep for some
time for sedimentation to occur and then
pour off the remaining liquid.
(ii) Centrifugation
•Centrifugation can also be used to
accelerate the process of phase separation.
31. Drying and densification
Removal of the remaining liquid (solvent) is
done by drying process, which accompanied
by shrinkage and densification.
Firing (or) crystallization
A thermal treatment (firing) is necessary to
enhance mechanical properties and
structural stability via sintering, densification.
33. Solvothermal Synthesis
Solvothermal synthesis involves the use of
solvent under high temperature (between
100°C to 1000°C) and moderate to high
pressure (1 atm to 10,000 atm) that facilitate
the interaction of precursors during
synthesis.
34. Method
A solvent like ethanol, methanol, 2-propanol is
mixed with certain metal precursors and the
solution mixture is placed in an autoclave kept
at relatively high temperature and pressure in
an oven to carry out the crystal growth. The
pressure generated in the vessel, due to the
solvent vapour, elevates the boiling point of
the solvent.
Example: Solvothermal synthesis of zinc
oxide
35. Solvothermal synthesis of
zinc oxide
• Zinc acetate dihydrate is dissolved in 2-
propanol at 50°C. Subsequently, the
solution is cooled to 0°C and NaOH is
added to precipitate ZnO. The solution is
then heated to 65°C to allow ZnO growth
for some period of time. Then a capping
agent (1-dodecanethiol) is injected into the
suspension to arrest the growth. The rod
shaped ZnO nano-crystal is obtained.
37. Electro-deposition
• Electro deposition is an important
technique for synthesizing metallic nano
materials with controlled shape and size.
Arrays of nano-structured materials with
specific arrangements can be prepared by
this method using an active template as a
cathode in an electrochemical cell.
39. The electro-deposition method consist of an
electrochemical cell. The cell usually
contains a reference electrode, a specially
designed cathodes and an anode. The
cathode, substrate on which electro-
deposition of the nano-structure takes place,
can be made of either non-metallic or
metallic materials. By using the surface of
the cathode, as a template, various desired
nano-structures can be synthesized for
specific application.
40. ELECTROSPINNING
Definition:
Electrospinning is a method of producing
ultrafine (in nanometers)Fibres by charging
and ejecting a polymer solution through a
spinneret under a high- voltage electric field
and to solidify(or) coagulate it to form a
filament.
41. Component
1.A high voltage power supply
2.A polymer reservoir that can maintain a
constant flow rate of solution.
3. A conductive needle as polymer source
connected to the high voltage power supply.
4. A conductive collector (plate, drum,etc)
43. Process
A polymer is dissolved in a suitable
solvent and is filled in the capillary reservoir
when sufficiently high voltage is applied to
create an electric field between the needle
tip and the collector, a charge accumulates
at the liquid surface when the electrostatic
repulsion is higher than the surface tension
the liquid meniscus is deformed into
conically shaped structure known as a
Taylor cones.
44. Once the Taylor cone is formed the
charged liquid jet is ejected towards the
collector, Depending upon the viscosity of
the solution solid fibre will be formed as the
solvent evaporates.
45. APPLICATION
• Electro spinning is used in diagnosis and treatment of
diabetes.
• Electrospun fibres are used in energy storage devices
such as solar cell, Fuel cell,super capacitors.
• It is also used in textiles for smart clothing, protecting
clothing and fire retardant fibres.
• It is used in sensors like gas sensors,chemical sensors
and fluorescence sensors.
• In biomedical it is used in drug delivery, artificial blood
vessel and wound dressing.
46. Application of Nano materials
Nanotechnology find significant impact on all most all the
industries and all areas of society causes unique beneficial
chemical physical and Mechanical properties that can be used for
a wide variety of applications
Medicine
1. Nanodrugs
Nano materials or used as Nano drugs for the cancer and
TB therapy
2. Laboratories on a chip
Nanotechnology is used in the production of laboratories on
a chip
47. 3.Nano- medibots
Nanoparticles function as Nano- medibots that
realise anticancer drug and treat cancer
4. Gold coated nanoshells
It converts light into heat energy bring the
destruction tumors
5. Gold nanoparticles as sensors
Gold nanoparticles undergo colour change during
their transition of nanoparticles
6. Protein analysis
Protein analysis can also be done using Nano
materials
7. Gold nanoshells for blood immunoassay
48. 8. Gold nanoshells in imaging optical properties of the
gold nanoshells or utilised for both imaging and therapy
9. Targeted drug delivery using gold nanoparticles
It involves slow and selectively subtracts to the
targeted organs
10. Repairing work
Nanotechnology is used to partially repair
neurological damage
49. Industries
1, As Catalyst
It depends on the surface area of the material. As nano-
particles have an appreciable fraction of their atoms at
the surface, its catalytic activity is good.
Eg: Bulk gold is chemically inert, where as gold nano
particles have excellent catalytic property.
2, In water purification
Nano filtration makes use of nano-porous
membrances having pores smaller than10nm. Dissolved
solids and colour producing organic compounds can be
filtered very easily from water.
50. 3, In fabric industry
The production of smrt clothing is
possible by putting a nano coating on the
fabric.
i) Embedding of nano particles on fabric
makes them stain repellent.
ii) Socks with embedded silver nano
particles fills all the bacteria and makes it
odour free.
51. 4, In Automobiles
i) Incorporation of small amount of nano particles in car
bumpers can make them stronger then steel.
ii) Specially designed nano-particles are used as fuel
additive to lower consumption in vehicles.
5, In food Industry
The inclusion of nano particles in food contact materials
can be used to generate novel type of packing materials and
containers.
6, In Energy sector
In solar power, nano- technology reduces the cost of
photovoltaic cells by 10 to 100times.
52. Electronics
1. Quandum wires are found to have high electrical
conductivity.
2.The integrated memory circuits have been found to be
effective devices
3. A transistor called NOMFET,is created by combining
gold nanoparticles with organic molecules
4. Nanowires are used to build transistors without p-n
junctions
5. Nano radios or the other important devices using
carbon nanotubes
6.MOSFET performs both as switches and as amplifiers.
53. Bio-materials
1, Nano materials are used as bone cement and bone
plates in hospitals.
2, It is also used as a material for joint replacements.
3, Nano technology is being used to develop miniature
video camera attached to a blind person’s glasses.
4,Nano materials are also used in the manufacture of
some components like heart valves and contact lenses.
5, Nano materials are also used in dental implants and
breast implants.
6, CNT’s are used as light weight shielding materials
for protecting electronic equipments against
electromagnetic radiation.
54. Properties of nanomaterials
Nano cluster:
•Nano cluster form an intermediate state of
matter between molecules and bulk
materials.
•There are fine aggregates of atoms, ions or
molecules. (a couple of hundred species)
with size less than 0% to 10 nm.
Eg: Nan (SF6)n(Tio2)n(Cu3Au)n
55. • Nano clusters can be classified based on
the nature of bonding present between the
atoms of the aggregate. They are (a)
Vander Waal’s Cluster (b) Ionic cluster (c)
Metallic Cluster (d) Network Cluster
a)Vander Waal’s Cluster:
• The atoms or molecules in a cluster are held
together by a weak force of attraction called
vander waals force of attraction.
• They have low melting and boiling point Eg.
(I2)n (SF6)n
56. b)Ionic Cluster:
The atoms in a cluster are held by
elctrostate force of attraction Eg. (Nacl)n
Metallic Cluster
Here the atoms are held by metallic bonds
metallic clusters are usually mono metallic
or bimetallic. They are widely used as
catalyst. Eg. Nan, (Cu3Au)n
57. C) Network cluster
•Here the atoms are held by strong covalent
bond. Eg., C60 (fullerene)
•Properties of Mettalic clusters:
•Magic Numbers: is the numbers of atoms
present in the clusters of critical sizes with
higher stability.
•Stable clusters contains 13, 55, 147, 309.
Metal atoms known as Magic numbers.
•Au55 is much stable than AU56.
58. • The reactivity of nano clusters are decreased due to
their decreased in size.
• The melting point of nano cluster are lower than the
bulk materials due to high surface to volume ratio
• The electronic structure is more confined then the
bulk materials.
2. Applications of Nano Clusters:
• Used a catalyst in many reactions
• Used a light emitting diode in quantum computers
• In micro electronics, telecommunications, sensors,
and optical data storage.
59. Nano Rods
•Nano Rods are ID nano structure , having
the shape of long sticks or rods.
•If the ratio of length to width 1-20, it is
called a nano rod
•Example: zinoxide, cds, gallium nitride nano
rods.
•Synthesis of Nano Rods:
• Nano rod are produced by direct
chemical synthesis.
60. Properties of nano rods:
• It exhibits optical and electrical
properties.
•Application:
•Nano rod finds application in display
technolies
•Used in the manufacture of micro mechanic
switches.
•They are used in energy harvesting and
light emithing devices.
•Nanorods have used as cancer therapy.
•Used as
61. Nano wires
• Nano wires are also ID nano structure. Nano wires are
often called as quabtum wire.
• If the ratio of length to width ratio exceeds 20, it is
called Nanowires.
• The diameter of the nanowire ranges fro 10-100mm.
• Eg:
• Metallic Nanowires – Au, Ni, Pt
• Nanowires of semi conductor – CraN, Si
• Nanowire of insulator – SiO2, TiO2
• Molecular Nanowire – DNA.
62. Properties:
• It is a one dimensional material shows
distinct optical, chemical thermal, and electrical
properties because of large surface area.
Applications:
• Nanowires find applications in the field of
electronice, opto electronic and sensor
deviced. Nanowires used to build transistors
without p-n junction. They are used a
additional in advanced composites.
63. Nanotubes
Nanotubes:
• Nanotubes are tiny hallow, tube like structure with
diameter of 1-100 mm and a length of few nm to microns.
Nanotubes may be organic or inorganic
Eg:
•Carbon Nanotube
•Silicon Nanotube
•DNA Nanotube
•Boron nitride Nanotube
64. Carbon Nanotubes:
• Carbon Nanotubes is a tabular form of carbon
with 1-3 nm diameter and a length of few nm to
microns.
•(allotropes of carbon, graphite, diamond, fullerene, and
Nanotube.)
• “When graphite sheet are rolled in to cylinder,
their edges join to each other form carbon Nano tubes.”
•Each carbon atom in the CNT is linked by covalent
bond.
•But number of Cnt alugn in to ropes are held together
by week vander waal force.
65. • Structure (or) types of carbon nanotubes:
Depending upon the way in which graphite
sheets are rolled. There are two types of
CNT are formed.
• Single – walled Nano tubes (SWNT)
• Multi-walled Nanotubes (MWNT)
• Single-walled Nanotubes (SWNT):
SWNT is formed by wrapping one atom
thide layer of grapheme into a cylinder,
having a diameter of 2nm and length of
100nm.
66. • Based on the orientation of the hexagon
lattire, they have three kinds of structure,
• Arm-chair structure, the lines of hexagon are
parallel to the axis of the nanotubes.
• Zig-Zag Structure the lines of carbon bond
are down the centre
• Chiral nano tubes: it exhibits a twist or sperial
around the nanotubes.
• It has been confirmed that armchair CNT are
metallic while zig-zag and chiral Nano tubes
are semi conducting
