There are two approaches for the manufacturing of nanomaterials:
The โtop-downโ approach, which involves the breaking down of large pieces of material to generate the required nanostructures from them.
The โbottom-upโ approach, which implies assembling single atoms and molecules into larger nanostructures.
Bottom-Up includes:-
Sol gel method
Template Assisted Synthesis
Chemical Precipitation
Microwave Assisted Synthesis
Self Assembly
Top-Down Includes:-
Mechanical Milling
High Pressure Torsion
Laser Ablation
Chemical Etching
Sputtering
TOP-DOWN AND BOTTOM-UP APPROACH IN SYNTHESIS OF NANOPARTICLES.pptx
1. TOP-DOWN AND BOTTOM-UP
APPROACH IN SYNTHESIS OF
NANOPARTICLES
Presented By-Lubhanshi Raje Shisodia
ROLL NUMBER-221240
MSc Biotechnology
2. Introduction
๏ต The synthesis of nanoparticles can be approached using either a top-down or
bottom-up approach, each with its own advantages and limitations. These
approaches are used in nanotechnology to create nanoparticles with specific
properties and characteristics.
3. Top-Down Approach:
๏ตIn the top-down approach, larger bulk
materials are broken down into smaller
nanoparticles through various
mechanical, chemical, or physical
methods. This method is used for
carving or sculpting a larger piece of
material into a desired shape at the
nanoscale.
4. Mechanical Milling:
Mechanical milling is usually
done using a planetary ball mill.
A refractory or steel ball's
energy transmission to a
powder relies on the rotating
(vibration) speed, size and
quantity of balls, ball-to-powder
mass ratio, duration and milling
environment. The shear action
of grinding produces
nanoparticles. Mechanical
milling is used to change the
properties of silver powders,
including disintegration of
particle aggregates, particle
shape, and particle surface
characteristics.
5. Laser Ablation:
Laser ablation or photoablation is
the process of removing material
from a solid surface by irradiating
it with a laser beam. At low laser
flux, the material is heated by the
absorbed laser energy and
evaporates or sublimates. At high
laser flux, the material is typically
converted to a plasma.
6. High Pressure Torsion:
In this the material sample is
subjected to very high pressure
typically in the gigapascals with the
help of equipment such as
hydraulic press machine along with
high pressure then sample is
subjected to torsion or shear this
means the material is twisted or
rotated along with pressure. Atoms
arrange themselves into regular,
repeating patterns to form a crystal
lattice The grain size is a measure
of how large or small these
individual crystalline structures are
within a given material
7. Chemical Etching:
In this technique chemical is used
for the synthesis of nanoparticles
materials like metals and ceramics
.In this technique basically the
metal is first coated with masking
material like wax โ this material
protect the areas that should not be
etched, then the masked sample is
submerged or exposed to the
chemical which ultimately helps in
breaking down the molecular bonds
which helps in the synthesis of
nanomaterials
8. Sputtering
The sputtering process involves the removal of
atoms or molecules from a solid target material
and their deposition onto a substrate to form a
thin film. The sputtering process takes place in
a vacuum chamber to eliminate the
interference of air or other gases. To initiate the
sputtering process, a low-pressure inert gas
(commonly argon) is introduced into the
chamber. The gas is ionized and accelerated
by an electric field, forming positively charged
ions. These ions are then directed toward the
target material. When the accelerated ions
strike the target material, they transfer energy
to the target atoms. This energy causes the
atoms in the target to be dislodged from the
target's surface. These dislodged atoms are
ejected with sufficient energy to become
vaporized. The vaporized target atoms travel
through the vacuum chamber and are
deposited onto the substrate, creating a thin
film.
9. Bottom-Up Approach:
๏ตA bottom-up approach to the synthesis of
nanoparticles involves building or growing
nanoparticles from individual atoms or
molecules. This approach allows for
precise control over the size, shape, and
composition of nanoparticles and is
commonly used in nanotechnology and
materials science.
10. The solโgel method
This method is based on the transformation of a sol (a colloidal suspension of
nanoparticles) into a gel-like network and the subsequent conversion of the
gel into solid nanoparticles. It consist of the metal cations called precursors is
added in the solvent to create a sol, then hydrolysis is done which helps in
breaking down the precursors into hydroxides then the hydrolysed particles
are condensed and form gel. Then the gel is carefully dried to remove solvent
leaving behind the nanopowder
11. Template-Assisted Synthesis:
In this technique templates or you
can say moulds are used for the
synthesis of nanoparticles, in these
templates precursor material is filled
. The precursor may be a metal salt or
a chemical compound depending on
the desired nanoparticle composition.
It is a technique used to produce
nanoparticles with controlled size,
shape, and properties by using
templates as scaffolds or molds for
the nanoparticles to form around.
12. Chemical Precipitation:
In this method, nanoparticles are
formed by the precipitation of ions
from a solution to create solid
particles. A reagent, often a
reducing agent or a precipitating
agent, is added to the precursor
solution. The reagent induces a
chemical reaction, causing the
metal ions to undergo a
precipitation reaction and form
solid nanoparticles. As the reaction
proceeds, solid nanoparticles form
and precipitate out of the solution.
The nanoparticles are then
separated from the solution
through processes like
centrifugation or filtration.
13. Microwave-Assisted Synthesis:
:
The reaction vessel containing the
precursor solution is placed in the
microwave cavity. When
microwaves are applied, the
molecules in the reaction mixture
absorb energy and become highly
energized. This localized and rapid
heating initiates the nanoparticle
synthesis. The tiny building blocks
in the liquid come together to form
the tiny particles. This is like
building a tiny LEGO structure
using the right pieces.
14. Self-Assembly:
Self-assembly is a fascinating process
where nanoparticles spontaneously
arrange themselves into organized
structures or patterns. This method is
widely used in nanotechnology to
create well-ordered and functional
materials.Nanoparticles are put down
in the liquid like water . Nanoparticles
as we know have the property of
magnet so they stick to each other like
magnets
In this the material sample is subjected to very high pressure typically in the gigapascals with the help of equipment such as hydraulic press machine along with high pressure then sample is subjected to torsion or shear this means the material is twisted or rotated along with pressure atoms arrange themselves into regular, repeating patterns to form a crystal lattice The grain size is a measure of how large or small these individual crystalline structures are within a given materia
In this technique chemical is used for the synthesis of nanoparticles materials like metals and ceramics .In this technique basically the metal is first coated with masking material like wax โ this material protect the areas that should not be etched .then the masked sample is submerged or exposed to the chemical which ultimately helps in breaking down the molecular bonds which helps in the synthesis of nanomaterials
The sputtering process involves the removal of atoms or molecules from a solid target material and their deposition onto a substrate to form a thin film. The sputtering process takes place in a vacuum chamber to eliminate the interference of air or other gases. To initiate the sputtering process, a low-pressure inert gas (commonly argon) is introduced into the chamber. The gas is ionized and accelerated by an electric field, forming positively charged ions. These ions are then directed toward the target material. When the accelerated ions strike the target material, they transfer energy to the target atoms. This energy causes the atoms in the target to be dislodged from the target's surface. These dislodged atoms are ejected with sufficient energy to become vaporized. The vaporized target atoms travel through the vacuum chamber and are deposited onto the substrate, creating a thin film.
This basically involves the building or growing up the nanoparticles from individual atoms or molecules
This method is based on the transformation of a sol (a colloidal suspension of nanoparticles) into a gel-like network and the subsequent conversion of the gel into solid nanoparticles. I t consist of the metal cations called precursors is added in the solvent to create a sol, then hydrolysis is done which helps in breaking down the precursors into hydroxides then the hydrolysed particles are condensed and form gel. Then the gel is carefully dried to remove solventleaving behind the nanopowder
In this technique templtes or you can say molds are used for the synthesis of nanoparticles in theses templates precursor material is filled . The precursor may be a metal salt or a chemical compound depending on the desired nanoparticle composition. is a technique used to produce nanoparticles with controlled size, shape, and properties by using templates as scaffolds or molds for the nanoparticles to form around.
In this method, nanoparticles are formed by the precipitation of ions from a solution to create solid particles. A reagent, often a reducing agent or a precipitating agent, is added to the precursor solution. The reagent induces a chemical reaction, causing the metal ions to undergo a precipitation reaction and form solid nanoparticles. As the reaction proceeds, solid nanoparticles form and precipitate out of the solution. The nanoparticles are then separated from the solution through processes like centrifugation or filtration.
The reaction vessel containing the precursor solution is placed in the microwave cavity. When microwaves are applied, the molecules in the reaction mixture absorb energy and become highly energized. This localized and rapid heating initiates the nanoparticle synthesis. The tiny building blocks in the liquid come together to form the tiny particles. This is like building a tiny LEGO structure using the right pieces.
Self-assembly is a fascinating process where nanoparticles spontaneously arrange themselves into organized structures or patterns. This method is widely used in nanotechnology to create well-ordered and functional materials.Nanoparticles are put down in the liquid like water . Nanoparticles as we know have the property of magnet so they stick to each other like magnets
