Cc
Cc
parle,
parle,
6
6
Nanomaterials
Nanomaterials
Syllabus
Syllabus
°°
Introduction to
to nano
nano -- materials
materials
Introduction
ee
Graphite
Graphite
e°
Fullerene
Fullerene
¢°
Carbon nanatubes
Carbon
nanatubes
e°
Nanowires
Nanowires
°°
Nanocones
Nanocones
°°
Haeckelites. Their
Their electronic
electronic and
and mechanical
mechanical properties
properties
Haeckelites.
e°
Production
CNTS
Production methods
methods for
for CNTS
°°
Applications of
Applications
of nano
nano materials
materials inin
i)
i)
Medicine
Medicine
ii)
ii)
Catalysis
Catalysis
iii)
iii)
Environmental
Environmental Technologies
Technologies
iv) Electronics
and related
iv)
Electronics and
relatedfields.
fields.
Vv)
Vv)
Mechanics.
Mechanics.
Applied Chemistry
Applied
Chemistry -- | (MU)
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—6.1
ee
6-2
6-2
Nanomaterials
Nanomaterials
Introduction §
The word
word nanotechnology
nanotechnology was
was used
used for
for the
the first
first time
time in
in 1974
1974 by
by Prof.
Prof. Nan’o
Nan’o
The
of Tokyo
of
Tokyo Science
Science University
University while
while explaining
explaining the
the silicon
silicon machined
machined down
downto
to
the small
the
small particle;
particle; smaller
smaller than
than one
one micron.
micron.
°°
Nanoscience can
Nanoscience
can be
be defined
defined as,
as, the
the study
study of
of phenomena
phenomena and
and manipulation
manipulation of
of
materials at
materials
at atomic,
atomic, molecular
molecular and
and macromolecular
macromolecular scales,
scales, where
where properties
properties
differ significantly
differ
significantly from
from those
those at
at aa larger
largerscale.
scale.
e6
Nanotechnology can
Nanotechnology
can be
be defined
defined as,
as, “the
“the design,
design, characterisation,
characterisation, production
production
and application
and
application of
of structures,
structures, devices
devices and
and systems
systems by
by controlling
controlling shape
shape and
and
size at
size
at the
the nanometre
nanometrescale.”
scale.”
|
6.2
Nanomaterials
6.2.1 Manufacture/Preparation
6.2.1
Manufacture/Preparation of
of Nanomaterials
Nanomaterials
>> [[ May
May 2009
2009! !] ]
e@
Materials
Materials comprising
comprising of
of particles
particles with
with aa size
size between
between 11 to
to 100
100 nm
nm (ie.
(ie.
10°m)
10
°m) are
are normally
normally considered
considered as
as nanomaterials.
nanomaterials.
ee
One nanometre
One
nanometre (nm)
(nm) is
is 10
10°m
°m i.e.
i.e. one
one thousand
thousand millionth
millionth of
of aa metre
metre which
which is
is
about the
about
the size
size of
of 66 carbon
carbon atoms
atoms in
in aa line
line or
or 10
10 hydrogen
hydrogen atoms
atomsin
in a line.
line.
e°
These objects
These
objects are
are too
too small
small to
to see
see without
without very
very powerful
powerful electron
electron microscope.
microscope.
8°
Nanomaterials can
Nanomaterials
can be
be of
of different
different shapes
shapes such
such aslike
as like rod,
rod, plate
plate or
or any
any other
other
complex geometry.
complex
geometry.
°°
@e
The spherical
The
spherical particles
particles which
which are
are less
less than
than 10
10 nm
nm arecalled
are called as
as clusters.
clusters.
_
Particles at
Particles
at nanoscale
nanoscale (100-0.2
(100-0.2 nm)
nm) show
show variation
variation in
in the
the properties
properties of
of
materials from
materials
from those
those at
at aa larger
larger scale
scale (Normal
(Normalsizes).
sizes).
ax
are
ow
Applied Chemistry
Applied
Chemistry -- | (MU)
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e°
6-3
6-3
Nanooma
Nan
mate
ter
rial
ial
ss
Below 100
Below
100 nm
nm with
with every
every lower
lower value
value the
the properties
properties like
like melting
melting point,
point,
colour
colour
i.e. wavelength
i.e.
wavelength of
of optical
optical transition,
transition, ionisation
ionisation potential,
potential, hardness,
hardness, catalytic
catalytic
activity and
activity
and selectivity,
selectivity, magnetic
magnetic properties
properties vary.
vary.
®e
These are
These
are the
the same
same properties
properties in
in materials
materials which
which remain
remain almost
almost constant,
constant,
whenparticles
when
particles are
are not
not in
in nano
nanoscales.
scales.
_e
_e
Due to
Due
to their
their remarkably
remarkably reduced
reduced size,
size, such
such materials
materials provide
provide challenging
challenging
usage in
usage
in the
the various
variousfield.
field.
Table 6.2.1
Table
6.2.1 : The
The sizes
sizes of
of nanoscale
nanoscale objects
objects
Object 0
Diameter
rogen atom
H-Hyd
H-Hydrogen
atom
0.1
0.1 nm
nm
uckminsterfullerence
Ceo-B
Ceo-Buckminsterfullerence
0.7
0.7 nm
nm
n nanot
ube (single wall)
Carbo
Carbon
nanotube(single
wall)
1.8nm
0.4-1.8nm
0.4-—
n atoms
66 carbo
carbon
atomsaligned
aligned
Inm
lnm
DNA
DNA
2nm
2nm
ns
Protei
Proteins
5-50 nm
nm
5-50
um Dot
CdSe
CdSe Quant
Quantum
Dot
2-10 nm
nm
2-10
ome
Ribos
Ribosome
25 nm
nm
25
Virus
Virus
0 nm
75-100
nm
75-10
Semiconductor Chip
Semiconductor
Chip Features
Features
90 nm*
90
nm*or
or shows
howe
Mitochondria
Mitochondria
500-1000 nm
500-1000
nm
Bacteria
Bacteria
1000-10000 nm
1000-10000
nm
Capillary (diameter)
Capillary
(diameter)
8000 nm
8000
nm
White blood
White
bloodcell
cell
10000 nm
10000
nm
*Currently the
the semiconductor
semiconductor chips
chips are
are being
being reduced
reduced to
to 20
20 nm
nm byby aa
*Currently
technique nanolithography.
technique
nanolithography.
Applied
Chemistry -- | (MU)
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(MU)
6-4
6-4
Va
Va
Nanomaterials
Nanomaterials
Nano-materials can.
Nano-materials
can. be
be manufactured
manufactured either
either of
of the
the following
following methods
methods
(modes)
(modes)
(i)
(i)
Top to
Top
to bottom
bottom
(ii) Bottom
(i)
Bottom up
up
e°
Top
Top to
to bottom
bottom method
method involves
involves milling
milling bulk
bulk material
material with
with normal
normal size
size
particles bulk
particles
bulk to
to small
small particles
particles (nanosize).
(nanosize).
e°
Bottom up
Bottom
up method
method involves
involves forming
forming objects
objects from
from individual
individual atoms
atoms or
or
molecules
molecules and
and joining
joining them.
them. e.g.
e.g. wood
wood madeupof
made up of cells
cells of
of trees
trees which
which are
are on
on
the
the nanoscale.
nanoscale.
°e
Wood
Wood comprises
comprises of
of cellulose
cellulose which
which is
is nothing
nothing but
but simple
simple glucose
glucose units
units
combined.
combined.
ee
In
high quantity
quantity of
In potatos,
potatos, which
which has
has high
of starch,
starch, comprises
comprises of
of repeating
repeating units
units of
of
glucose.
glucose.
82
But
But we
we use
use wood
wood andpotatoes
and potatoes for
for different
different purposes.
purposes.
°e
This
This isis because,
because, they
they differ
differ in
in linkages
linkages of
of glucose.
glucose. These
These are
are natural
natural
polymers.
polymers.
Fig. 6.2.2
Fig.
6.2.2 :: The
The chemical
chemical composition
composition of
of starch
starch
Thus extraordinary
Thus
extraordinary properties
properties shown
shown by
by nanomaterials
nanomaterials are
are due
due to
to the
the
difference in
difference
in the
the arrangement
arrangementof
of simple
simple materials.
materials.
+i
es
a
;
mee
Applied Chemistry
Applied
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vw
°
°
ae
6-5
6-5
Nanomaterials
Nanomateria
ls
The
The properties
properties of
of materials
materials can
can be
be different
different at
at the
the nanoscale
nanoscale for
for two
two main
main
reasons.
reasons.
°°
1.
1.
Increase in
Increase
in relative
relative surface
surface area,
area, and
and
2.
2.
Quantumeffects.
Quantum effects.
These factors
These
factors can
can change
change or
or enhance
enhance properties
properties such
such asreactivity,
as reactivity, strength
strength
andelectrical
and electrical characteristics.
characteristics.
°°
With decrease
With
decreasein
in size
size of
of particle,
particle, aa greater
greater number
number of
of atoms
atoms are
are found
found at
at the
the
surface as
surface
as compared
compared to
to those
those inside.
inside.
ee
For example,
For
example, aa particle
particle of
of size
size 30
30 nm
nm has
has 5%
5% of
of its
its atoms
atomsonits
on its surface,
surface,
At 10
At
10 nm
nm 20%
20% of
of its
its atoms,
atoms,
At
its atoms.
At 33 nm
nm 50%
50% of
ofits
atoms.
°8
Thus nanoparticles
Thus
nanoparticles have
have aa much
much greater
greater surface
surface area
area per
per unit
unit mass
mass as
as
compared with
compared
with larger
largerparticles.
particles.
°®
The
The catalytic
catalytic chemical
chemical reactions
reactions occur
occur mainly
mainly on
on surfaces.
surfaces. Thus
Thus given
given mass
mass
of
of material
material in
in nanoparticulate
nanoparticulate form
form will
will be
be much
much more
more reactive
reactive than
than the
the
same mass
same
mass of
of material
material made
madeup
up of
oflarger
larger particles.
particles.
Example :: U.S.
Example
U.S. silver
silver dollar
dollar
°°
The silver
The
silver dollar
dollar contains
contains 26.96
26.96 grams
gramsofcoin
of coin silver,
silver, has
has a
a diameter
diameterof
of about
about
40
40 mm,
mm, and
and has
has a
a total
total surface
surface area
area of
of approximately
approximately 27.70
27.70 square
square
centimeters.
centimeters.
°°
If the
If
the same
same amount
amount of
of coin
coin silver
silver were
were divided
divided into
into tiny
tiny particles
particles —— say
say
11 nanometer
nanometer in
in diameter
diameter —— the
the total
total surface
surface area
area of
of those
those particles
particles would
would be
be
\w
ww
11,400 square
11,400
square meters.
meters.
°°
Thus the
Thus
the surface
surface area
area increases
increases by
by 4.115
4.115 million
million times
times than
than the
the surface
surface area
area
of the
of
the silver
silver dollar,
dollar, when
when not
not in
in nanosize.
nanosize.
[Sane
eerie
ene erp
eer rrreen es
| =
|
eA
ni
Applied
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|
6-6
6-6
Nanomaterials
Nanomaterials
In other
In
other materials
materials such
such as
as crystalline
crystalline solids,
solids, as
as the
the size
size of
of their
their structural
structural
components decreases,
decreases, there
is much
much greater
greater interface
area within
the
components
there is
interface area
within the
material;
material; this
this can
can greatly
greatly affect
affect both
both mechanical
mechanical and
and electrical
electrical properties.
properties.
°°
Most metals
Most
metals are
are made
made up
up of
of small
small crystalline
crystalline grains;
grains; the
the boundaries
boundaries
between
the grain
grain slow
arrest the
the propagation
propagation of
of defects
defects when
when the
between the
slow downor
down or arrest
the
material is
material
is stressed,
stressed, thus
thus giving
givingit
it strength.
strength.
ee
If these
If
these grains
grains can
can be
be made
made very
very small,
small, or
or even
even nanoscale
nanoscale in
in size,
size, the
the
interface area
interface
area within
within the
the material
material greatly
greatly increases,
increases, which
which enhances
enhances its
its
strength.
strength.
°°
For example,
example, nanocrystalline
nanocrystalline nickel
nickel is
as strong
strong as
as hardened
hardenedsteel.
For
is as
steel.
8°
Understanding
Understanding surfaces
surfaces and
and interfaces
interfaces isis aa key
key challenge
challenge for
for nanomaterials.
nanomaterials.
°e
The known
The
known allotropes
allotropes of
of carbon
carbon are,
are, (i)
(i) Graphite
Graphite (ii)
(ii) Diamond.
Diamond. But
But
Nanotechnology has
Nanotechnology
has helped
helpedto
to get
get the
the third
third allotrope
allotrope of
of carbon.
carbon. Fullerenes
Fullerenesor
or
Coo.
Ceo.
16.3
46.3 Graphite
Graphite yA
yA
°°
Allotrope of
Allotrope
of carbon
carbon i.e.
i.e. graphite
graphite acts
acts
as
as aa lubricant.
lubricant. It
It also
also forms
forms aa carbon
carbon
“e
“G
C€
DH
eam
fiber material
fiber
material used
used in
in tennis
tennis rackets
rackets
and
and bicycles.
bicycles.
°e
milOC¢
“O
“‘
These varied
These
varied uses
uses of
of graphite
graphite are
are
been
been mainly
mainly due
due to
to its
its structure
structure as
as
3.
JO
oat
p.
aae
A?
shownin
shown
in Fig.
Fig. 6.3.1.
6.3.1.
Fig. 6.3.1
Fig.
6.3.1 : Molecular
Molecular model
model of
of graphite
graphite
°e
Each
Each of
of the
the carbon
carbon atoms
atoms is
is bound
bound to
to three
three other
other carbon
carbon atoms
atoms in
in the
the same
same
plane, at
plane,
at aa molecular
molecularlevel.
level.
|
————==
—_
ne
el
Applie
Appliedd Chemis
Chemisttry
ry -- | (MU)
(MU)
6-7
6-7
Nanerfa
sienontetiats
aieiie
°«
The
The planar
planar surface
surfacess do
do not
not have
have covalen
covalentt links
links and
and are
are therefore
therefore free
free is
to
move relative
moverelati
to one
ve to
one another,
another, which
which gives
gives graphite
graphite its
its lubricant
lubricant properties.
properties.
e®
Because of
Because
of the
the structural
structural uniqueness,
uniqueness, graphite
graphite has
has slippery
slippery movement
movement in
in
molecular form.
molecular
form.
#6.4
q6.4
Fullerene
Fullerene
§
ao
~
>» [[ Dec.
Dec. 2007,
2007, Dec.
Dec. 2008,
2008, May
May 2009,
2009, Dec.
Dec. 2009
2009 !! ]}
°°
The fullerenes
The
fullerenes can
can be
be considered,
considered, after
after graphite
graphite and
and diamond,
diamond,to
to be
be the
the third
third
well-defined allotrope
well-defined
allotrope of
of carbon.
carbon.
°e
Fullerenes were
Fullerenes
werefirst
first isolated
isolated in
in 1990,
1990, in
in considerable
considerable quantity.
quantity.
ee
The molecule
The
molecule was
was named
named after
after R.
R. | Buckminster
Buckminster Fuller,
Fuller, the
the inventor
inventor of
of
geodesic domes,
geodesic
domes, which
which conform
conform to
to the
the same
same underlying
underlyingstructural
structural formula.
formula.
°°
AA hollow,
hollow, pure
pure carbon
carbon molecule
molecule in
in which
which the
the atoms
atoms lie
lie at
at the
the vertices
vertices of
of a.a.
polyhedron with
polyhedron
with 12
12 pentagonal
pentagonal faces
faces and
and any
any number
numberof
of hexagonal
hexagonalfaces.
faces.
ee
(When graphite
(When
graphite was
was vaporised
vaporised with
with aa short-pulse,
short-pulse, high-power
high-power laser)
laser) itit
turned into
turned
into Fullerence
Fullerence —— Cgpo.
Cgpo.
°°
But this
But
this was
was not
not aa practical
practical method
method for
for making
making large
large quantities.
quantities.
Fig. 6.4.1
Fig.
6.4.1 :: Chemical
Chemical structure
structure of
of Buckminster-fullerene-C,,
Buckminster-fullerene-C,,
°°
Each carbon
Each
carbon isis bound
bound to
to three
three other
other carbons
carbons in
in aa _ pseudo-spherical
pseudo-spherical
arrangement
arrangement consisting
consisting of
of alternating
alternating pentagonal
pentagonal and
and hexagonal
hexagonal rings,
rings, in
in
the manner
the
mannerofa
of a soccer
soccer ball.
ball. Hence
Hence its
its nickname,
nickname, buckyball.
buckyball.
Applied
Applied Chemistry
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6-8
6-8
Nanomaterials
Nanomaterials
s
Every
Every carbon
carbon is
is equivalent.
equivalent. NMR
NMR spectrum
spectrum of
of Cg
Ceo reveals
reveals a
a single
single line.
line.
e
Buchminster
Buchminster fullerene
fullerene is
is aa beautiful
beautiful thing
thing it
it was
was found
found as
as aa byproduct
byproduct of
of
| Ap
soot formation.
formation.
soot
.
Scrape the
Scrape
the inside
inside of
of the
the chimney
chimney and
and you
you will
will get
get few
few buckyballs
buckyballs on
on the
the
finger.
finger.
8
Properties and
Properties
and applications,
ition
Fullerences are
Fullerences
are spheroidal
spheroidal organic
organic molecules.
molecules. Following
Following are
are the
the physical
physical
and
of fullerences,
fullerences,
and chemical
chemical properties
propertiesof
e
Fullerene
Fullerene and
and its
its derivatives
derivatives show
show superconductivity
superconductivity and
and ferro-magnetism.
ferro-magnetism.
ns fullerenes
See
fullerenes are
are used
used in
in synthetic,
synthetic, pharmaceutical,
pharmaceutical, and
and industrial
industrial
)
pplications, as
drugs or
as inhibitor
inhibitor of
of the
the HIV
HIV protease,
protease, to
to make
make new
new drugs
oraapplications,
proteins.
proteins.
—_—
_—
ee
aCeo
Ceo fullerene
fullerene are
are used
used in
in cosmetics
cosmetics preparation
preparation applicable
applicable in
in halting
halting the
the
4
——
SO
process
of aging.
processof
aging.
°
The
Theothertype
other type of
of fullerene
fullerene Cgp
Cgp can
can act
act as
as aa very
very good
good MRI
MRI contrast
contrast agent.
agent.
e
They
They can
can be
be useful
useful in
in light
light emitting
emitting diodes
diodes (LED),
(LED), molecular
molecular electronics
electronics and
and
computing,
computing, as
as lubricants,
lubricants, rocket
rocket fuel
fuel etc.
etc.
e
Fullerene
due to
to its
Fullerene C59,
C59, shows
shows odd
odd magnetic
magnetic and
and electronic
electronic properties
properties due
its shape
shape
being intermediate
being
intermediate between
between aa sphere
sphere and
and aa disk.
disk.
°
Quantum
Quantum dots
dots are
are crystals
crystals so
so small
small that
that their
their properties
properties are
are subject
subject to
to
quantum
quantum effects.
effects. They
They are
are also
also called
called as
as zero
zero directional
directional objects.
objects.
°
The
Thesize
size of
of Quantum
Quantum dot
dot isis larger
larger than
than an
an atom
atom though
though the
the difference
difference isis
negligible.
negligible. The
The smallest
smallest such
such quantum
quantum dot
dot contains
contains only
only 33 atoms
atoms like
like water.
water.
ea
Be
ee
:
=
.s
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(MU)
°°
6-9
6-9
Nanomaterials
Nanomaterials
Same
Same quantum
quantum dots
dots are
are made
made up
up of
of virtual
virtual matier
matier composed
composed of
of confined
confined
electrons.
electrons.
f
f
.,
°°
.
Such
Such quantum
quantum dots
dots exist
exist in
in crystal
crystal format
format though
though their
their massis
mass is very
very low.
low.
ee
Quantum dot
dot is
is a
a nanoparticle
nanoparticle with
with unusual
unusual properties.
properties.
Quantum
°°
Quantum
Quantum well
well are
are formed
formed when
when the
the electrons
electrons are
are traped
traped in
in an
an island
island of
of
conducting
conducting and
and semiconducting
semiconducting material
material which
which is
is surrounded
surrounded entirely
entirely by
by an
an
insulator.
insulator. These
These traps
traps are
are called
called as
as quantum
quantum wells.
wells.
ll
°°
The
The traps
traps are
are of
of very
very thin
thin layers
layers similar
similar to
to computer
computer chips
chips —
— nanometer
nanometer
thick.
thick.
II
°°
It
It was
was found
found that
that electrons
electrons can
can movefreely
move freely only
only in
in two
two dimensions.
dimensions.
rr
ee
The
The distance
distance they
they travel
travel in
in the
the third
third dimension
dimension was
was found
found to
to be
be smaller
smaller
than
than the
the wavelengthof
wavelength of electrons.
electrons.
3
sqossceemmrnianat senescence ia
YO
(pins
"|
~.
(6.6
§6.6 Carbon
Carbon Nanotubes
Nanotubes (CNT’s)
(CNT’s) {| f
>
> [[ May
May 2008,
2008, May
May 2010
2010! ]]
4d
®e
Carbon
sheets are
Carbon particles
particles as
as graphene
graphene sheets
are made
made into
into tubular
tubular forms
forms called
called as
as
Carbon
nanotubes.
Carbon nanotubes.
.e
e°
They
their lengths
lengths are
up to
They have
have diameters
diameters of
of few
few nanometers
nanometers and
and their
are up
to several
several
micrometers.
micrometers.
0O
ee
They
They were
were discovered
discovered in
in 1991
1991 by
by lijima.
lijima.
®e
Carbon nanotubes
future applications.
Carbon
nanotubes have
have very
very important
important future
applications.
Structural features
features
| Structural
ie°
S74
s
Each
made up
Each nanotube
nanotube is
is made
up of
of a
a hexagonal
hexagonal network
network of
of covalently
covalently bonded
bonded
carbon
atoms.
carbon atoms.
’
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
6-10
6-10
Nanomaterials
Nanomaterials
Carbon nanotubes
Carbon
nanotubesare
are of
of two
two types
types:
:
(i)
(i)
single-walled
single-walled
(ii)
(ii) multi-walled.
multi-walled.
carbon nanotube
nanotube (SWNT)
(SWNT) consists
consists of
of aa single
single graphene
graphene
AA single-walled
single-walled carbon
cylinder
multi-walled carbon
carbon nanotube
nanotube (MWNT)
(MVWNT) consists
consists of
of
cylinder whereas
whereas aa multi-walled
several graphene
several
graphenecylinders
cylinders which
which are
are arranged
arrangedin
in concentric
concentric form.
form.
Dueto
Due
to such
such structures,
structures, these
these CNTS
CNTS show
showelectronic,
electronic, mechanical,
mechanical, optical
optical and
and
chemical characteristics,
chemical
characteristics, thermal
thermal conductivity,
conductivity, density,
density, and
and lattice
lattice structure.
structure.
which make
which
make them
them highly
highly useful
useful for
for many
many application.
application.
The
The intrinsic
intrinsic properties
properties of
of CNTS
CNTS depend
depend on
on the
the diameter.
diameter.
6.7
6.7
/Methods of Preparation
Methodsof
Preparation for
for CNTS
CNTS and
and Fullerenes
Fullerenes
|
There
There are
are five
five methods
methodsfor
for preparation
preparation of
of CNTs,
CNTs, and
and Fullerenes.
Fullerenes.
Arc method
Arc
method
Laser method
Laser
method
Chemical Vapour
Chemical
Vapour Deposition
Deposition [CVD]
[CVD]
Ball
Ball milling
milling
Flame synthesis
Flame
synthesis
6.7.1
6.7.1
Arc
Arc Method
Method
A
°
This isis the
This
the first
first method
method for
for producing
producing CNTs
CNTs and
and fullerenes
fullerenes in
in reasonable
reasonable
quantities.
quantities.
°©
In this
In
this method,
method, an
an electric
electric current
current is
is applied
applied across
across two
two carbonaceous
carbonaceous
|
|
}
electrodes in
electrodes
in an
an inert
inert gas
gas atmosphere.This
atmosphere. This isis called
called plasma
plasma arcing.
arcing.
_
—_
e°
The
The carbon
carbon arc
arc discharge
discharge method,
method, has
has been
been initially
initially used
used for
for producing
producing Ceo
Ceo
A
—|
fullerenes.
fullerenes.
|?
|?
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
ee
6-11
6-11
Nanomaterials
Nanomaterials
It isis the
It
the most
most common
common and
and perhaps
perhaps easiest
easiest way
way to
to produce
produce CNTs,
CNTs,asit
as it isis
rather simple.
rather
simple.
ee
It involves
It
involves the
the evaporation
evaporation of
of one
one electrode
electrode as
as cations
cations followed
followed by
by deposition
deposition
Sieeae
a
at the
at
the other
other electrode.
electrode. This
This plasma-based
plasma-based process
processis
is similar
similar to
to electroplating
electroplating
—
——
——_—___—_—
-
ee
process.
process.
ofof
———
—_———
°e
dd
This method
This
method creates
creates CNTs
CNTs through
through arc-vaporization
arc-vaporization of
of two
two carbon
carbon rods
rods
-- placed
placed end
end to
to end,
end, separated
separated by
by approximately
approximately 1mm,
1mm, in
in an
an enclosure
enclosurethatis
that is
usually filled
usually
filled with
with inert
inert gas
gas at
at low
low pressure.
pressure.
e®
Recent investigations
Recent
investigations have
have shown
shown that
that itit isis also
also possible
possible to
to create
create CNTs
CNTs
with the
with
the arc
arc method
methodin
in liquid
liquid nitrogen.
nitrogen.
—_—_
—_—_
°e
AA direct
direct current
current of
of 50
50 to
to 100
100 A,
A, driven
driven by
by aa potential
potential difference
difference of
of
approximately 20
approximately
20 V,
V, creates
creates aa high
high temperature
temperature discharge
discharge between
between the
the two
two
electrodes.
electrodes.
|.
le
The discharge
The
discharge vaporizes
vaporizes the
the surface
surface of
of one
one of
of the
the carbon
carbon electrodes,
electrodes, and
and
forms aa small
forms
small rod-shaped
rod-shaped deposit
deposit on
on the
the other
other electrode.
electrode.
eie
The fullerenes
The
fullerenes appear
appear in
in the
the soot
soot that
that is
is formed,
formed, while
while the
the CNTs
CNTs are
are
deposited on
deposited
on the
the opposing
opposingelectrode.
electrode.
°6
This technique
This
technique produces
produces aa complex
complex mixture
mixture of
of components,
components, and
and requires
requires
further purification
further
purification
to separate
to
separate the
the CNTs
CNTs from
from the
the soot
soot and
and the
the residual
residual
catalytic metals
catalytic
metals present
present in
in the
the crude
crude product.
product.
6.7.
6.7.
aser
aser Method
Method
»» [[ Dec.
Dec. 2007
2007 | }}
"=
°°
In 1996
In
1996 CNTs
CNTswerefirst
were first synthesized
synthesized using
using aa dual-pulsed
dual-pulsed laser
laser and
and achieved
achieved
yields of
yields
of >70
>70 wt%
wt% purity.
purity.
=ne
Seo
Yeo
Ns3
In this
In
this method
method the
the samples
samples were
were prepared
prepared by
by laser
laser vaporization
vaporization of
of graphite
graphite
:|
rods with
rods
with aa 1:
1: 11 catalyst
catalyst mixture
mixture of
of Cobalt
Cobalt and
and Nickel
Nickel at
at 1200°C
1200°C in
in flowing
flowing
|
argon,
argon, followed
followed by
by heat
heat treatment
treatment in
in aa vacuum
vacuum at
at 1000°C
1000°Cto
to get
get the
the Ceo
Ceo and
and ~~
a4
|
- other
other fullerenes.
fullerenes.
—
So
=
-_
;:
ae
a
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
®°
6-12
6-12
;.
Nanomaterials
Nanomaterials
ack}
a
The
minimizes the
the amount
The use
use of
of two
two successive
successive laser
laser pulses
pulses minimizes
amount of
of carbon
carbon
—_
os
deposited as
deposited
as soot.
soot.
°°
The
Thesecond
second laser
laser pulse
pulse breaks
breaks up
up the
the larger
largerparticles
particles ablated
ablated by
by the
thefirst
first one,
one,
and feeds
and
feeds them
them into
into the
the growing
growing nanotube
nanotubestructure.
structure.
°@
EE
The material
The
material produced
produced by
by this
this method
method appears
appears as
as aa mat
matof
of “ropes”,
“ropes”, 10-20nm
10-20nm
in diameter
in
diameter and
and up
up to
to 100um
100um or
or more
morein
in length.
length.
°°
ti
Each rope
Each
rope is
is found
found to
to consist
consist primarily
primarily of
of aa bundle
bundle of
of single
single walled
walled
nanotubes, aligned
nanotubes,
aligned along
along aa common
commonaxis.
axis.
e°
By varying
By
varying the
the temperature,
temperature, the
the catalyst
catalyst composition,
composition, and
and other
other process
process
parameters, the
parameters,
the average
average nanotube
nanotube diameter
diameter and
and size
size distribution
distribution can
can be
be
varied.
varied.
°°
Arc-discharge and
Arc-discharge
and laser
laser vaporization
vaporization are
are currently
currently the
the principal
principal methods
methods for
for
obtaining small
obtaining
small quantities
quantities of
of high
high quality
quality CNTs.
CNTs.
Drawbacksof
Drawbacks
of Arc
Arc and
and laser
laser method
method
Both methods
Both
methods involve
involve evaporating
evaporating the
the carbon
carbon source,
source, Hence
Hence to
to increase
increase
production to
production
to the
the industrial
industrial level
level using
using these
these approaches,
approaches, is
is difficult.
difficult.
Both methods
Both
methods produce
produce CNTs
CNTsin
in highly
highly tangled
tangled forms,
forms, mixed
mixed with
with unwanted
unwanted
forms of
forms
of carbon
carbon and/or
and/or metal
metal species.
species.
Hence, CNTs
Hence,
CNTs produced
produced are
aredifficult
difficult to
to purify,
purify, manipulate,
manipulate, and
and assemble
assemble for
for
building nanotube-device
building
nanotube-device architectures
architectures for
for practical
practical applications.
applications.
Ais
Ais
Chemical Vapor
Chemical
Vapor Deposition
Deposition [CVD]
[CVD]
In this
In
this method,
method, hydrocarbon
hydrocarbon such
such as
as acetylene
acetylene is
is subjected
subjected to
to chemical
chemical
vapour deposition
vapour
deposition catalytically
catalytically using
using metal
metal catalyst,
catalyst, such
such as
as cobalt
cobalt or
or iron.
iron.
Method is
Method
is established
established for
for last
last 20
20 years
years and
and has
has been
been in
in use
use for
for producing
producing
various carbon
various
carbon materials
materials such
such as
as carbon
carbonfibers,
fibers, filaments
filamentsetc.
etc.
Hydrocarbon used
Hydrocarbon
used are,
are, acetylene,
acetylene, ethylene,
ethylene, methane
methaneetc.
etc.
|
zm
s
7
zu
Sie
[|
Applied Chemistry - | (MU)
Applied Chemistry - | (MU)
6-13
6-13
Nanomateri
Nanomaterials
als
Table 6.7.1
_ Table
6.7.1 :: Someof
Some of the
the sources,
sources,catalyst,
catalyst, temperatures
temperatures are
are as
asfollows
follows ::
a
Carbon
Carbon source
source : af oe
_ Temp
Temp _ee
oA
Ethylene
Ethylene
545°C 900°C
900°C
545°C
Catalyst
Catalyst
.Ni/Fe/CO
.Ni/Fe/C
O
SWCNTand
SWCNT and
MWCNT
MWCNT
.
n
H./CH4
| HL/CH,
1000°C catalytic
catalytic | CO/Ni/Fe
CO/Ni/Fe
1000°C
d
Acetylene
Acetylen
e
1S
Product
Product
|.
High yield
yield of
of
onon| High
decomposition
decompos
ition
MgO
MgO
SWCNT
SWCNT
600°C
== 600°C
Cobalt
Cobalt
SWCNT
SWCNT
e
MWCNT
MWCNT
wr
r
Carbon source
source with
with| >> 800°C
800°C
Carbon
H)/CHy,
H/CH,
oxide solid
solid solution
solution
oxide
atmosphere,
any| powders
powders
atmosphe
re, any
(Reducible
to nonnon(Reducibl
e to
metal catalyst
catalyst
metal
containing
CNT
containi
ng CNT
Metal catalyst
catalyst
Metal
CWCNT
CWCNT
reducible
reducible
se
se
:
.
transition
transitio
n
|
oxide)
oxide)
/
CH,
CH4
or - =||
or
oxides
oxides
with one
one or
or more
more
with
|
ad
metal
metal
500°C
>> 500°C
Decomposition
Decomposition
MWCNT
MWCNT
:
Any
source. | >
600°C
Any carbon
carbon source.
> pone
a1cetyl
| | | e.g.eg.<.8: acetylene
acetylene
ogog
i
po
i
|
(main)
(main)
/
(minor
(minor
quantity)
quantity)
|
‘al
‘al
Composite
Composit
e
C/zeolite catalyst
C/zeolite
catalyst
.
bee|
eee
|
+Few MWCNT
+ Few MWCNT
—
~
\
\:%
\
ay,
Sa
eee
Applied Chemistry
Chemistry -- | (MU)
(MU)
Applied
j
A
6-14
6-14
Nanomaterials
Nanomaterials
6.7.4
6.7.4 Ball
Ball Milling
Milling
Ball
for the
Ball milling
milling and
and subsequent
subsequent annealing
annealing isis aa simple
simple method
methodfor
the production
production
of
of CNTs.
CNTs.
CNTs
CNTs of
of carbon
carbon and
and boron
boron nitride
nitride can
can be
be produced
produced from
from their
their respective
respective
powders
powders by
by thermal
thermal annealing.
annealing.
These
These CNTs
CNTs are
are fully
fully nanoporous
nanoporous microstructures.
microstructures. Method
Method consists
consists of
of
placing
placing graphite
graphite powder
powder into
into a
a stainless
stainless steel
steel container
container containing
containing four
four
hardenedsteel
hardened
steel balls.
balls. The
The container
container is
is purged,
purged, and
and argon
argonis
is introduced.
introduced.
The milling
milling isis carried
carried out
out at
at room
room temperature
temperature for
for up
up to
to 150
150 hours.
hours. On
On
The
completion of
completion
of milling,
milling, the
the powder
powder isis annealed
annealed under
under an
aninert
inert gas
gas flow
flow at
at
temperatures
temperatures of
of 1400°C
1400°C for
for six
six hours.
hours.
The mechanism
The
mechanism of
of this
this process
process is
is not
not known,
known, but
but by
by using
using the
the ball
ball milling
milling
process
process nanotube
nanotube nuclei
nuclei are
are formed,
formed, and
and by
by using
using annealing
annealing process
process growth
growth
of
of nanotubeis
nanotube is activated.
activated.
It isis observed
It
observed that
that this
this method
method produces
produces more
more multi
multi walled
walled nanotubes
nanotubes
(MWCNT)andfew
(MWCNT)
and few single
single walled
walled nanotubes
nanotubes (SWCNT).
(SWCNT).
6.7.5
6.7.5
Other
Other Methods
Methods
CNTs can
CNTs
can also
also be
be produced
produced by
by diffusion
diffusion flame
flame synthesis,
synthesis, electrolysis,
electrolysis, use
use of
of
solar
solar energy,
energy, heat
heat treatment
treatment of
of aa polymer,
polymer, and
and low-temperature
low-temperature solid
solid
pyrolysis.
pyrolysis.
In flame
flame synthesis,
synthesis, combustion
combustion of
portion of
of the
hydrocarbon gas
gas provides
provides
In
of aa portion
the hydrocarbon
the elevated
the
elevated temperature
temperature required,
required, with
with the
the remaining
remaining fuel
fuel conveniently
conveniently
serving as
the required
required hydrocarbon
hydrocarbon reagent.
serving
as the
reagent.
Thus the
the flame
flame constitutes
efficient source
of both
both energy
energy and
and
Thus
constitutes an
an efficient
source of
hydrocarbon
material.
hydrocarbon raw
raw material.
Combustion synthesis
be used
for high-volume
commercial production,
Combustion
synthesis can
can be
used for
high-volume commercial
production,
by modifying
by
modifying various
various parameters of
of process.
process.
a!
a
a=
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU) —_
:
6.8
Properties of Carbon
6-15
6-15
Nanotubes
Nanomaterials
Nanomaterials
|
a,
Bectiieal Conductivity
onHC
Conductivity
(1)
(1)
CNTscanbe
CNTs
can be highly
highly conducting,
conducting, and
and hence
hence can
can be
besaid
said to
to be
be metallic.
metallic.
(2)
(2)
Their
Their conductivity
conductivity has
has been
been shown
shown to
to be
be aa function
function of
of (1)
(1) chirality,
chirality,
(2)
(2) degree
degree of
of twist
twist (3)
(3) diameter.
diameter.
(3)
(3)
CNTs
CNTs can
can be
be either
either metallic
metallic or
or semi-conducting
semi-conducting inin- their
their electrical
electrical
behavior.
behavior. Conductivity
Conductivity in
in MWNTsis
MWNTs is quite
quite complex.
complex.
(4)
(4)
The resistivity
The
resistivity of
of the
the SWCNT
SWCNT ropes
ropes isis found
found to
to be
be of
of the
the order
order of
of
10-4 ohm-cm
10-4
ohm-cm at
at 27°C.
27°C. Thus
Thus SWCNT
SWCNT ropes
ropes are
are the
the most
most conductive
conductive
carbon fibers
carbon
fibers known.
known.
(5)
(5)
They are
They
are able
able to
to sustain
sustain much
much higher
higher stable
stable current
current densities,
densities, as
as high
high
as 10-13
as
10-13 A/cm?.
A/cm?.
Jt has
has been
been reported
reported that
that individual
individual single
single walled
walled nanotubes
nanotubes may
may
(6) It
(6)
contain defects.
contain
defects. These
These defects
defects allow
allow the
the single
single walled
walled nanotubes
nanotubesto
to act
act
as transistors.
as
transistors. Likewise,
Likewise, joining
joining CNTs
CNTs together
together may
may form
form transistortransistorlike
like devices.
devices.
nanotube with
with aa natural
natural junction
junction (where
(where aa straight
straight metallic
metallic section
section
(7) AA nanotube
(7)
isis joined
joined to
to aa chiral
chiral semiconducting
semiconducting section)
section) behaves
behaves as
as aa rectifying
rectifying
diode —— that
diode
thatis,
is, aa half-transistor
half-transistor in
in aa single
single molecule.
molecule.
(8)
(8)
ItIt has
has also
also recently
recently been
been reported
reported that
that single
single walled
walled nanotubes
nanotubes can
can
route
route electrical
electrical signals
signals at
at speeds
speeds up
up to
to 10
10 GHz
GHz when
when used
used as
as
interconnects on
interconnects
on semi-conducting
semi-conducting devices.
devices.
b)
b)}
Strength and
Strength
and Elasticity
Elasticity
(1)
(1)
The carbon
The
carbon atoms
atoms of
of aa single
single sheet
sheet of
of graphite
graphite form
form aa planar
planar
honeycomblattice,
honeycomb
lattice, in
in which
which each
each atom
atom isis connected
connected via
via strong
strong chemical
chemical
bondto
bond
to three
three neighboring
neighboring atoms.
atoms.
Because of
of these
these strong
strong bonds,
bonds, the
the basal
basal plane
plane elastic
elastic modulus
modulus of
of
(2) Because
(2)
graphite isis one
graphite
one of
of the
the largest
largest of
of any
any known
known material.
material.
Z
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
6-16
6-16
rf
:
Nanomaterials
Nanomaterials
(3)
(3)
For this
For
this reason,
reason, CNTs
CNTs are
are expected
expected to
to be
be the
the ultimate
ultimate high-strength
high-strength
fibers.
fibers. Single
Single walled
walled nanotubes
nanotubes are
are stiffer
stiffer than
than.steel,
steel, and
and are
are very
very
resistant
resistant to
to damage
damage from
from physical
physicalforces.
forces.
(4)
(4)
Pressing on
Pressing
on the
the tip
tip of
of aa nanotube
nanotube will
will cause
cause itit to
to bend,
bend, but
but without
without
damageto
damage
to the
the tip.
tip. When
When the
the force
force is
is removed,
removed, the
the nanotube
nanotube returns
returns to
to
its original
its
original state.
state.
(5)
(5)
This property
This
property makes
makes CNTs
CNTs very
very useful
useful as
as probe
probe tips
tips for
for very
very highhighresolution scanning
resolution
scanning probe
probe microscopy.
microscopy.
(6)
(6)
The current
The
current Young’s
Young’s modulus
modulusvalueof
value of single
single walled
walled nanotubes
nanotubesis
is about
about
11 TeraPascal,
TeraPascal, but
but this
this value
value has
has been
been widely
widely disputed,
disputed, and
and aa value
value as
as
high as
high
as 1.8
1.8 Tpa
Tpa has
has been
been reported.
reported.
(7)
(7)
Young’s modulus
Young’s
modulus depends
depends on
on the
thesize
size and
and chirality
chirality of
of the
the single
single walled
walled
nanotubes, ranging
nanotubes,
ranging from
from 1.22
1.22 Tpa
Tpa to
to 1.26
1.26 Tpa.
Tpa.
Ch,
oe
cc
They have
They
have calculated
calculated aa value
value of
of 1.09
1.09 Tpa
Tpa for
for aa generic
generic nanotube.
nanotube.
Thermal Conductivity
Thermal
Conductivity and
and Expansion
Expansion
(1)
(1)
CNTs exhibit
CNTs
exhibit superconductivity
superconductivity below
below 26°K
26°K (approximate
(approximate -253°C).
-253°C).
(2)
(2)
CNTs can
can adopt
adopt electrical
electrical properties
properties and
and behave
behave as
semiconductorsor
CNTs
as semiconductors
or
even as
even
as metals.
metals.
(3)
(3)
They are
They
are exceptionally
exceptionally strong
strong and
andstiff
stiff against
against axial
axial strains.
strains.
(4)
(4)
CNTs
possess high
CNTspossess
high flexibility
flexibility against
against non-axial
non-axial strains.
strains.
(5)
(5)
CNTs
are used
in nanoscale
and
CNTs are
used in
nanoscale molecular
molecular electronics,
electronics, sensing
sensing and
actuating devices,
actuating
devices, or
or as
as reinforcing
reinforcing additive
additive fibers
fibers in
in functional
functional
composite materials.
composite
materials.
(6)
(6)
CNTs show
CNTs
show very
very high
high thermal
thermal conductivity.
conductivity.
(7)
(7)
Polymeric
Polymeric materials
materials reinforced
reinforced by
by CNTs
CNTs also
also significantly
significantly improve
improve the
the
thermal and
thermal
and thermomechanical
thermomechanical properties
properties of
of the
the composites.
composites.
d
d
ield
ield Emission
Emission
(1)
(1)
When
electrons from
from aa metal
vacuum, under
When electrons
metal tip
tip are
are tunneled
tunneled into
into vacuum,
under
application
application of
of aa strong
strong electric
electric field.
field.
(2)
(2)
Field emission
Field
emission isis resulted
resulted the
the small
small diameter
diameter and
and high
high aspect
aspect ratio
ratio of
of
CNTs isis very
very favorable
favorable for
for field
field emission.
emission.
CNT'T's
,
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)--
(3)
(3)
6-17
6-17
,
Nanomaterials
Nanomaterials
Even
Even for
for moderate
moderate voltages,
voltages, aa strong
strong electric
electric field
field develops
develops at
at the
the free
free
end
end of
of supported
supported CNTs
CNTs because
becauseof
of their
their sharpness.
sharpness.
(4) This
This phenomenon
phenomenon was
was observed
observed by
by de
de Heer
Heer and
and co-workers
co-workers at
at EPFL
EPFL in
in
(4)
1995.
1995.
(5)
(5)
These
These field
field emitters
emitters are
are found
found to
to be
be superior
superior to
to conventional
conventionalelectron
electron
sources
sources and
and hence
hence they
they find
find their
their way
way into
into all
all kind
kind of
of applications,
applications,
most
most importantly
importantly flat-panel
flat-panel displays.
displays.
(6)
(6)
It
It isis remarkable
remarkable that
that after
after only
only five
five years
years Samsungactually
Samsung actually realized
realized a
a
very
very bright
bright color
color display,
display, which
which will
will be
be shortly
shortly commercialized
commercialized using
using
this
this technology.
technology.
(7)
(7)
Studying the
Studying
the field
field emission
emission properties
properties of
of multi
multi walled
walled nanotubes,
nanotubes,
Bonard
Bonard and
and co-workers
co-workers at
at EPFL
EPFL observed
observed that
that together
together with
with electrons,
electrons,
light
light is
is emitted
emitted as
as well.
well. This
This luminescence
luminescence is
is induced
induced by
by the
the electron
electron
field
field emission,
emission, since
since it
it is
is not
not detected
detected without
without applied
applied potential.
potential. This
This
light
light emission
emission occurs
occurs in
in the
the visible
visible part
part of
of the
the spectrum,
spectrum, and
and can
can
sometimes
sometimes be
be seen
seen with
with the
the naked
naked eye.
eye.
e)
e)
High
High Aspect
Aspect Ratio
Ratio
;
(1)
(1)
CNTs
CNTs represent,
represent, high
high aspect
aspect ratio
ratio about
about 1000
1000: :1.
1.
(2)
(2)
The
lower loading
The high
high aspect
aspect ratio
ratio indicates
indicates that
that aa lower
loading of
of CNTs
CNTs isis needed
needed
compared
compared to
to other
other conductive
conductive additives
additives to
to achieve
achieve the
the same
sameelectrical
electrical
conductivity,
conductivity, such
such as
as carbon
carbon black,
black, chopped
chopped carbon
carbon fiber
fiber or
or stainless
stainless
steel fiber.
steel
fiber.
(3)
(3)
Due to
Due
to low
low loading
loading of
of CNTs
CNTs the
the toughness,
toughness, of
of polymer
polymer resins’
resins’ isis
presented especially
presented
especially at
at low
low temperatures,
temperatures, as
as well
well as
as maintaining
maintaining other
other
key
key performance
performance properties
properties of
of the
the matrix
matrix resin.
resin.
CN
(4) CN
(4)
have proven
have
proven to
to be
be an
an excellent
excellent additive
additive to
to impart
impart electrical
electrical
onductivity in
onductivity
in plastics.
plastics.
f)f)
ighly
ighly Absorbent
Absorbent
(1)
(1)
The large
The
large surface
surface area
area gives
gives high
high absorbency
absorbency to
to CNTs
CNTs which
which make
make
them ideal
them
ideal for
for use
use in
in air,
air, gas,
gas, and
and water
waterfiltration.
filtration.
we
ie
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
(2)
(2)
6-18
6-18
Nanomaterials
Nanomaterials
Replacing
Replacing activated
activated charcoal
charcoal with
with CNTs
CNTs in
in certain
certain ultra
ultra high
high purity
purity
applications, has
applications,
has been
been successful.
successful.
eesnageg
“
jo.
6.9 Applications
Applications of
of Carbon
Carbon Nanotubes
Nanotubes
—§
The
The most
most important
important application
application of
of carbon
carbon nanotubes
nanotubesare:
are:
°
Ascatalyst
As
catalyst support
support
e
In
In batteries
batteries Fuel
Fuel Cells:
Cells: He,
He, Li
Li storage
storage
°
As
As field
field emitters
emitters for
for instrumentation
instrumentation . capacitors
capacitors
°
As
electrodes in
Aselectrodes
in electrochemistry
electrochemistry
e
In microscopy
microscopy
In
°
As nanotube
nanotube sensors
sensors
As
°
Asdiodes,
diodes, transistors
transistors and
and capacitors
capacitors
As
°
As nanoscale
reactors, ion
ion channels
channels
As
nanoscale reactors,
°
As
transport
As membranesfor
membranes for molecular
molecular transport
°
Asfilling
materials in
in polymer
polymer composites
composites
As
filling materials
| 6.10 Nanowires
|
»> [[ May
May 2010
2010!
! ]]
°
AA nanowire
nanowire is
is an
an extremely
extremely thin
thin wire
wire with
with a
a diameter
diameter of
of the
the order
order of
of aa few
few
nanometers
(nm) or
or less,
meters. |
nanometers (nm)
less, where
where 11 nm
nm == 10°?
10° meters.
e
Nanowires are
are like
ordinary wires
an abnormally
abnormally less
less thickness
thickness 10
10
Nanowires
like ordinary
wires with
with an
atoms
atoms diameter,
diameter, length
length can
can be
be longer
longer even
even up
up to
to 1000
1000 nm
nm ie.
i.e. 11 um.
um.
°
Nanowiresare
Nanowires
are synthesized
synthesized gradually
gradually just
just like
like crystal
crystal growth.
growth.
°
Nanowires of
various combinations
combinations of
Nanowires
of various
of materials
materials which
which not
not only
only carries
carries
current
current but
but also
also information
information are
are not
not only
only synthesized
synthesized but
but are
are being
being
manufactured.
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
6-19
6-19
Nanomaterials
Nanomaterials
Manufacture
Manufacture
°e
There are
There
are two
two processes
processes in
in nanotechnology
nanotechnology by
by which
which nanowires
nanowires can
can be
be
manufactured are
manufactured
are
(i)
(i)
suspension
suspension
(ii)
(ii)
deposition.
deposition.
Suspension
Suspension
°e
In
suspended nanowire
nanowireis
by its
its ends
ends in
in an
an evacuated
evacuated
In this
this method
method aa suspended
is held
held by
chamber,
chamber, and
and then
then isis chemically
chemically etched
etched or
or bombarded
bombarded with
with high-speed
high-speed
atoms
atomsor
or molecules
molecules to
to reduce
reduce its
its diameter.
diameter.
°°
Another
Another method
method involves
involves indenting
indenting the
the surface
surface of
of aa wire
wire in
in the
the center
center of
of aa
suspended span,
span,raising
the temperature,
temperature, and
and then
then stretching
stretching the
the wire
wire while
while
suspended
raising the
itit is
is near
near its
its melting
melting point.
point.
Deposition
Deposition
ee
In
In this
this method
method deposited
deposited nanowire
nanowire is
is fabricated
fabricated on
on aa surface
surface consisting
consisting of
of
some
some non-conducting
non-conducting substance
substance such
suchasplastic
as plastic or
or glass.
glass.
°°
The
The process
process isis similar
similar to
to that
that by
by which
which semiconductor
semiconductor chips
chips are
are grown,
grown,
except
except that
that the
the result
result is
is aa linear
linear (one-dimensional)
(one-dimensional) structure
structure rather
rather than
than aa
flat (two-dimensional)
(two-dimensional) or
or solid
solid (three-dimensional)
(three-dimensional) structure.
structure.
flat
Application
Application
e°
Nanowires can
Nanowires
can be
be usedinfield
used in field effect
effect transistors
transistors (FET),
(FET), light
light emitting
emitting diodes
diodes
(LEDs),
(LEDs), nanolasers,
nanolasers, solar
solar cells,
cells, thermoelectric
thermoelectric devices,
devices, optical
optical detectors,
detectors,
chemical
chemical andbiological
and biological sensors.
sensors.
°°
Fields
Fields expected
expected to
to benefit
benefit from
from nanotechnology
nanotechnology include
include water
water purification,
purification,
sanitation,
sanitation, agriculture,
agriculture, alternative
alternative energy
energy (particularly
(particularly photovoltaics),
photovoltaics), home
home
and
and business
business construction,
construction, computer
computer manufacturing,
manufacturing, communications,
communications, and
and
medicine
medicine disease
disease detection
detection and
and intervention.
intervention.
jj6.11
»» [[ Dec.
Dec. 2007,
2007, May
May 2009,
2009, Dec.
Dec. 2009
2009 ! ]]
°@
Carbon nanocones,
Carbon
nanocones, were
were discovered
discovered in
in 1994
1994 which
which are
are the
the most
most simple
simple
example of
example
of the
the nanostructured
nanostructured carbon.
carbon.
°®
They are
They
are made,
made, of
of the
the hexagonal
hexagonal plane
plane with
with aa different
different number
number of
of
pentagonal
pentagonal defects,
defects, more
more precisely,
precisely, from
from one
onetofive.
to five.
Applied Chemistry
Apptied
Chemistry -- | (MU)
(MU)
6-20
6-20
Nanomaterials
Nanomaterials
°°
Eachcut,
Each
cut, or
or the
the pentagonal
pentagonaldisclination,
disclination, has
has the
the angle
angle 22 xx /6.
/6.
ee
The
positive disclination)
The fivefold
fivefold (or
(or positive
disclination) could
could be
be stable,
stable, but
but the
the most
most stable
stable
configuration for
configuration
for more
more than
than one
one defect
defect isis the
the configuration,
configuration, where
where they
they are
are
separated
separated by
by hexagons.
hexagons.
Fig. 6.11.1
Fig.
6.11.1 : The
The carbon
carbon nanocone
nanocone
ii
°°
|:
|
The nanocones
The
nanoconesare
are produced
produced by
by
(i)
(i)
Carbon condensation
Carbon
condensation on
on aa graphite
graphite substrate
substrate
Gi)
Gi)
Pyrolysis
Pyrolysis of
of heavy
heavy oil.
oil.
(ii)
(iii) Laser
Laser ablation
ablation of
of graphite
graphite targets.
targets.
6e
In
In laser
laser ablation,
ablation, graphite
graphite surface
surface isis heated
heated with
with intensive
intensive short
short laser
laser pulse.
pulse.
°e
The graphite
The
graphite evaporates
evaporates some
some number
number of
of atoms
atoms from
from the
the graphene
graphene sheet,
sheet,
and
as shown
shown above.
above.
and other
other atoms
atoms rearrange
rearrange into
into the
the conical
conical surface
surface as
The growth
The
growth of
of nanocones
nanoconesis
is yet
yet under
under study.
study.
»» [[ Dec.
Dec. 2007,
2007, Dec.
Dec. 2008,
2008, Dec.
Dec. 2009,
2009, May
May 2010
2010 ! }}
ae
The presence
The
presence of
of defects
defects such
such as
as pentagons
pentagons and
and heptagons
heptagons in
in fullerenes
fullerenes
modifies the
modifies
the electronic
electronic properties.
properties.
e°
AA new
new hypothetical
hypothetical type
type of
of graphene
graphene sheet,
sheet, which
which admits
admits pentagons,
pentagons,
heptagons
heptagons and
and hexagons,
hexagons, has
has been
been proposed,
proposed, noting
noting that
that the
the number
number of
of
heptagons
heptagons and
and pentagons
pentagons should
should be
be the
the same
same in
in order
order to
to compensate
compensate for
for the
the
negative
negative curvature
curvature of
of the
the heptagons
heptagons and
and the
the positive
positive curvature
curvature of
of the
the
pentagons
pentagons(Fig.
(Fig. 6.12.1).
6.12.1).
es
"
-
i
Ys
he
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
e
6-22
6-22
Nanomaterials
Nanomaterials
These arrangements
These
arrangements are
are now
now called
called ‘Haeckelites’
‘Haeckelites’ in
in honour
honour of
of Ernst
Ernst Haeckel,
Haeckel,
aa German
German zoologist
zoologist who
who produced
produced aa beautiful
beautiful drawing
drawing of
of radiolaria
radiolaria (micro(microskeleta
skeleta of
of zoo-plankton),
zoo-plankton), in
in which
which heptagonal,
heptagonal, hexagonal
hexagonal and
and pentagonal
pentagonal
rings were
rings
were observed.
observed.
Properties
Properties
e
They
They show
show metallic
metallic behaviour.
behaviour.
°
Thus,
Thus, it
it isis possible
possible to
to roll
roll up
up Haeckelite
Haeckelite sheets
sheets to
to form
form nanotubes,
nanotubes, which
which will
will
be conductors,
conductors, independent
independentof
the diameter
diameter and
andchirality.
be
of the
chirality.
°
Another property
Another
property of
of Haeckelite
Haeckelite tubes
tubes retain
retain stiffness
stiffness of
of classical
classical CNTs,
CNTs,
composed
composed of
of only
only hexagons;
hexagons; (the
(the Young’s
Young’s modulus
modulus of
of Haeckelite
Haeckelite tubes
tubes is
is
around
around 1.0
1.0 TPa.)
TPa.)
e
In addition,
In
addition, Haeckelites
Haeckelites also
also exhibit
exhibit local
local rugosity
rugosity due
due to
to the
the local
local curvature
curvature
introduced by
introduced
by the
the presence
presence of
of heptagons
heptagons and
and pentagons
pentagons(Fig.
(Fig. 6.12.1).
6.12.1).
| 6.13
of Nanomaterials
6.13 Applications
Applications of
Nanomaterials
|
>»> [[ Dec.
Dec. 2008,
2008, May
May 2009
2009 !! ]]
Some important
Some
important current
current and
and potential
potential short
short and
and long-term
long-term applications
applications of
of
nanomaterials
nanomaterials are
are as
as follows.
follows.
6.13.1” Nenomechanios
618.0”
Nenomechanios 5“
Molecules
conformation due
to change
in temperature,
pH, light,
Molecules can
can change
change conformation
due to
change in
temperature, pH,light,
electrontransferetc.
electrontransfer
etc.
°
Recently
Recently nanoscale
nanoscale electromechanical
electromechanical rotor
rotor of
of size
size 300
300 nm
nm rectangular
rectangular blade
blade
mounted
mounted on
on multiwall
multiwall nanotube
nanotube was
was functionalised.
functionalised.
°
Using
Using electron
electron microscopy
microscopy itit isis shown
shown that
that as
as aa voltage
voltage isis applied
applied to
to the
the
stator
stator electrode,
electrode, the
the metal
metal blade
blade orientation
orientation changes.
changes.
°
Thus
Thus further
further developments
developments in
in this
this area
area can
can be
be deflectable
deflectable mirrors,
mirrors, detection
detection
of motion
of
motionofof microfluide
microfluide system
system etc.
etc.
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
6-23
§-23
Nanomaterials
Nanomaterials
4 una
|
4Ue
Single molecule
molecule nanocar,
nanocar, thermally
thermally driven,
driven, with
Single
like
with fullerene
fullerene based
based wheel
wheellike
reported.
also reported.
motion
is also
motionis
Mechanical applications
Mechanical
applications are
are mainly
mainly dependent
dependent on
on the
the very
very strong
strong carbon
carbon
nanotubes which
nanotubes
which are
areasstiff
as stiff and
and hard
hard as
as diamond
diamond but
buthighly
highly flexible.
flexible.
These tubes
These
tubes are
are semi-conducting
semi-conducting or
or metallic.
metallic. The
The composite
composite textile
textile material
material
containing carbon
containing
carbon nanotubes
nanotubes and
and polymer
polymer polyvinyl
polyvinyl alcohcl
alcohol are
are being
being
produced.
produced.
The nanotubes
The
nanotubes with
with 30
30 um
umin
in diameter
diameterand
and tensile
tensile strength
strength of
of 1.4
1.4 to
to 1.8
1.8 GPa
GPa
are
are reported
reported to
to be
be produced
produced and
and have
have future
future applications
applications in
in helmedts,_
helmeds,_
protective textiles,
protective
textiles, bullet
bullet proof
proof cloths
clothsetc.
etc.
Cutting tools
Cutting
tools made
made of
of nanocrystalline
nanocrystalline materials,
materials, such
such as
as tungsten
tungsten carbide,
carbide,
tantalum carbide
tantalum
carbide and
and titanium
titanium carbide,
carbide, are
are more
more wear
wear and
and erosionerosion-
resistant,
resistant,
and
and
last
last
longer
longer
than
than
their
their
conventional
conventional
(large-grained)
(large-grained)
counterparts.
counterparts.
Drilis used
Drilis
used to
to bore
bore holes
holes in
in circuit
circuit boards.
boards.
Living cells
Living
cells are
are described
described as
as living
living machines.
machines. Nanotechnology
Nanotechnology builds
builds up
up the
the
tiny machines
tiny
machines through
through these
these biological
biological systems,
systems, DNA-RNA,
DNA-RNA, self
self assembly
assembly
etc. resulting
etc.
resulting in
in moreefficient
more efficient machines.
machines.
In chemical
In
chemical reactions
reactions e.g.
e.g. when
when small
small amount
amount of
of tin
tin are
are deposited
deposited on
on Cu
Cu
(111) single
single crystal
crystal at
at 290
290 K,
K, it
it is
is observed
observed that
that tin
tin crystal
crystal proceed
proceed
(111)
spontaneously
spontaneously in
in a
a systematic
systematic fashion
fashion leaving
leaving behind
behind bronzealloy.
bronze alloy.
Lubricants
Lubricants
Nanospheres of
Nanospheres
of inorganic
inorganic materials
materials could
could be
be used
used as
as lubricants,
lubricants, in
in essence
essence
by acting
by
acting as
as nanosized
nanosized ball
ball bearings’.
bearings’.
The controlled
The
controlled shape
shape make
make them
them more
more durable
durable than
than conventional
conventional solid
solid
lubricants and
lubricants
and wear
wear additives.
additives.
These nanoparticles
These
nanoparticles reduce
reduce friction
friction between
between metal
metal surfaces,
surfaces, particularly
particularly at
at
e
a
high normal
high
normalloads.
loads.
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
6.13.2
6.13.2
6-24
6-24
Nanomaterials
Nanomaterials
Medicine vA
Medicine
we
»» [[ May
May 2008,
2008, May
May 2009
2009! ]]
‘‘
Nanomaterials are
Nanomaterials
are of
of the
the size
size 11 xx 10°
10° m.
m, Hence
Hence they
they are
are comparable
comparable or
or even
even
smaller than
smaller
than aa single
single cell
cell 10
10 —— 100
100 um
um and
and virus
virus 20
20 —— 450
450 nm,
nm, protein
protein 55 —— 50
50
nm. Thus
nm.
Thus the
the materials
materials can
can freely
freely move
move through
through tissues,
tissues, they
they can
can also
also bind
bind
to
to a
a biological
biological system.
system.
.s
Endothelian layers
Endothelian
layers of
of fast
fast growing
growing tumour
tumour tissues
tissues are
are porous
porous thus
thus these
these
nanoparticles
nanoparticles can
can pass
pass through
through them
them bringing
bringing out
out aa specialised
specialised effect
effect as
as aa
medicine.
medicine.
‘e
Drug delivery
Drug
delivery isis done
done through
through self
self assemblies
assemblies like
like phospholipids
phospholipids or
or through
through
block
block polymers.
polymers. The
The drugs
drugs molecules
molecules can
can be
be interrelated
interrelated in
in lipohilic
lipohilic wall
wall
which
which acts
acts like
like aa cell
cell membrane.
membrane.
.‘
Liposome
Liposome protects
protects the
the drug
drug from
from being
being assimilated
assimilated during
during digestion
digestion or
or
metabolised in
in certain
certain environments.
environments. Hydrophobic
Hydrophobic character
character of
of the
the liposome
liposome
metabolised
dissolves
dissolves drug
drug and
and allows
allows itit toto pass
pass through.
through blood,
blood, brain
brain unaffected.
unaffected.
®s
When itit arrives
When
arrives at
at aa specific
specific targetted
targetted site
site the
the drug
drug isis released
released due
due to
to
temperature or
temperature
or PH
PH at
at the
the site
site inflamed
inflamed of
of the
the organ
organ or
or the
the concentration
concentration at
at
the site
the
site lyposomes
lyposomes have
have PH
PH 44 —— 55 and
and tumour
tumourtissues
tissues also
also have
have PH
PH 44 --5.5.
Thus
Thus lyposomes
lyposomes open
open up
up at
at PH
PH 4-5
4-5 allowing
allowing the
the drug
drugto
to be
be released.
released.
°°
Magnetic components
Magnetic
components like
like FesO.
FesO. magnetite
magnetite or
or FesO3
FesO3 are
are coated
coated with
with SiOe
SiOz
and then
and
then with
with biocompatible
biocompatible polymer.
polymer.
®®
This polymer
This
polymer has
has attachment
attachment point
point for
for the
the attachment
attachment with
with toxic
toxic drugs
drugs or
or
anti
anti bodies.
bodies. A
A magnet
magnet isis placed
placed outside
outside the
the body
body near
near the
the target
target site
site to
to
capture the
the magnetic
particles, flowing
flowing in
in a
a circulatory
circulatory system.
system.
capture
magnetic particles,
ss
Similarly the
Similarly
the action
action of
of cytostatic
cytostatic anticancer
anticancer drugs
drugs isis localised
localised there
there by
by
reducing
reducing side
side effects
effects on
on the
the patients
patients body
body especially
especially arthritis,
arthritis, dextrane
dextrane
coated
coated with
with iron
iron oxides
oxides are
are used
used and
and are
are extracted
extracted via
via liver
liver treatment.
treatment.
°°
For localised
localised destruction
destruction of
of cancer
cancer cells
cells this
this technique
technique isis used.
used.It
called as
as
For
It isis called
artificially induced
artificially
induced hyperthermia.
hyperthermia. Magnetic
Magnetic particles
particles are
are dispersed
dispersed through
through
out
out the
the target
target tissue.
tissue.
Ap
a
a
Applied
Applied Chemistry
Chemistry -- || (MU)
(MU)
6-25
6-25
Nanomaterials
Nanomaterials
An
An alternating
alternating magnetic
magnetic field
field of
of sufficient
sufficient strength
strength 00 ~-15
15 KA
KA M™
M°?and
and
frequency
frequency
0.05 -— 1.2
1.2 MHz
MHz isis applied
applied to
to heat
heat up
up the
the deceased
deceased area
area and
and
0.05
maintained at
at 42°C
42°C for
for 30
30 mings,
mins, thus
thus destroying
destroying cancer
cancer tissues,
tissues, retaining
retaining
maintained
healthy tissues
tissues intact.
intact.
healthy
Magnetic particles
particles are
are also
also used
used for
tagging the
the specific
specific biological
biological entities
entities
Magnetic
for tagging
like lung
lung cancer
cancer cells,
cells, certain
certain bacteria,
bacteria, urological
urological cancer
cancer cells
cells and
and also
red
like
also red
blood cells
cells thus
making itit possible
possible to
to remove
remove these
these cells
cells through
through magnetic
magnetic
blood
thus making
Magnetic particles
particles are
are also
also used
used as
as contrast
contrast enhancing
enhancing agents
agents in
in the
the MRI.
MRI.
Magnetic
This shortens
shortens the
the relaxation
relaxation time
time Ti
T: and
and Te
Tefor
the tissue.
tissue.
This
for the
Larger particles
Larger
particles of
of 30
30 nm
nm are
are rapidly
rapidly collected
collected at
at liver,
liver, spleen
spleen where
where as
as
particles
particles
<< 10
10 nm
nm are
are collected
collected in
in the
the reticuloendothetial
reticuloendothetial cells
cells through
through out
out the
the body
body
1.8.
1.6. lymph
lymph nodes
nodes bone
bone marrow
marrow etc.
etc.
Tumourcells
Tumour cells do
do not
not have
have reticuloendothetial
reticuloendothetial system
system of
of healthy
healthy cells.
cells. Thus
Thus
by contrast
contrast the
the site
these particle
can be
located in
in MRI.
MRI.
by
site with
with these
particle tissue
tissue can
be located
Thus making
making it
it easier
accurate to
to detect
tumeur, liver
liver tumour
tumour and
Thus
easier accurate
detect brain
brain tumour,
and
lymph
lymph nodes.
nodes.
Thus
Thus coating
coating of
of incompatible
incompatible metallic
metallic material
material with
with ceramic
ceramic type
type of
of coating
coating
or interface
interface
or
formed by
by self
self assembly
of monomolecular
monomolecular layers
layers play
play an
an
formed
assembly of
important
important role
role in
in medicalfield
medical field giving
giving biocompatibility
biocompatibility and
and application.
application.
Nanomaterials
Nanomaterials due
due to
to their
their specific
specific size
size interface
interface grain
grain boundaries
boundaries posses
posses
unique
unique properties.
properties. e.g.
e.g. hydrophobic
hydrophobic anddirt
and dirt repelling
repelling molecules
molecules —
— reflecting
reflecting
the
the lotus
lotus effect
effect triggered
triggered as
as a
a function
function of
of temperatureor
temperature or light
light exposure.
exposure.
a
—
separation through
through fluid
flow.
separation
fluid flow.
/we
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
6.13.3
6.13.3 Catalysts
Catalysts
6-26
6-26
Nanomaterials
Nanomaterials
tL
tL
»
» [[ May
May 2008,
2008, May
May 2009
2009 |! }}
In general,
In
general, nanoparticles
nanoparticles have
have aa high
high surface
surface area,
area, and
and hence
hence provide
provide higher
higher
catalytic
catalytic activity.
activity.
Nanotechnologies are
Nanotechnologies
are enabling
enabling changes
changes in
in the
the degree
degree of
of control
control in
in the
the
production of
production
of nanoparticles,
nanoparticles, and
and the
the support
support structure
structure on
on which
which they
theyreside.
reside.
ItIt isis possible
possible to
to synthesise
synthesise metal
metal nanoparticles
nanoparticles in
in solution
solution in
in the
the presence
presence of
of
aa surfactant
surfactant to
to form
form highly
highly ordered
ordered monodisperse
monodisperse films
films of
of the
the catalyst
catalyst
nanoparticles on
nanoparticles
on aa surface.
surface.
This allows
This
allows more
more uniformity
uniformity in
in the
the size
size and
and chemical
chemical structure
structure of
of the
the
catalyst, which
catalyst,
which in
in turn
turn leads
leads to
to greater
greater catalytic
catalytic activity
activity and
and the
the production
production
of
of fewer
fewer byproducts.
byproducts.
ItIt may
may also
also be
be possible
possible to
to engineer
engineer specific
specific or
or selective
selective activity.
activity.
These
These more
more active
active and
and durable
durable catalysts
catalysts could
could find
find early
early application
application in
in
cleaning
cleaning up
up waste
waste streams.
streams.
This
This will
will be
be particularly
particularly beneficial
beneficial ifif it
it reduces
reduces the
the demand
demand for
for platinumplatinumgroup
group metals,
metals, whose
whose use
use in
in standard
standard catalytic
catalytic units
units isis starting
starting to
to emerge
emerge as
as
aa problem,
problem, given
given the
the limited
limited availability
availability of
of these
these metals.
metals.
6.13.4
in Environmental
A
6.13.4 Applications
Applications in
Environmental Technology
Technology ye
At present
At
present the
the use
use of
of nanomaterials
nanomaterials in
in environmental
environmental technology
technology isis not
not yet
yet
explored but
explored
but isis on
on the
the way
wayto
to be
be in
in use.
use.
Nanoporus
Nanoporus aluminosilicates
aluminosilicates (zeolites)
(zeolites) are
are being
being used
used in
in radio
radio nuclides
nuclides and
and
poisonous
poisonous transition
transition metals
metals removal
removal from
from waste
waste water
water due
due to
to their
their high
high
adsorption.
adsorption.
Nanporous
Nanporous membranes
membranes polymer
polymer membranes
membranes with
with definite,
definite, desired
desired adjustable
adjustable
pore size
pore
size are
are used
used as
as mnicrofilters
microfilters for
for dust
dust particles
particles from
from air
air and
and water.
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
6-28
6-28
Nanomaterials
Nanomaterials
At
At present
present atomic
atomic scale
scale memory
memory is
is possible.
possible. A
A bit
bit isis encoded
encoded by
by the
the pres/abs
pres/abs
of
-Si atom
atoms prevent
prevent or
or absorb
of —Si
atom inside
inside 55 xx 44 == 20
20 atoms.
atoms. Thus
Thus 19
19 atoms
absorb the
the heat,
heat
energy.
energy. Thus
Thus storage
storage capacity
capacity of
of hard
hard disks
disks is
is increased.
increased. Thin
Thin films
films of
of organic
organic
materials emitting
emitting light
(OLED) are
known. Thin
transistors TFT
TFT and
and thin
thin
materials
light (OLED)
are known.
Thin film
film transistors
film
film organic
organic photovoltaic
photovoltaic cells
cells are
are known.
known.
The deposition
The
deposition at
at aa reasonable
reasonable cost
cost isis possible
possible because
because of
of organo
organo inorganic
inorganic
metallic
metallic compounds
compounds which
which are
are normally
normally the
the self
self assembeled,
assembeled, nanomaterials.
nanomaterials. They
They
can form
can
form thin
thin films
films by
by simple
simple techniques
techniques the
the spray,
spray, spin
spin cooling
cooling vapour
vapour
deposition, inkjet
deposition,
inkjet printing
printing etc.
etc.
a)
a)
Displays
Displays
(1)
(1)
The huge
The
huge market
market for
for large
large area,
area, high
high brightness,
brightness, flat-panel
flat-panel displays,
displays, as
as
used in
used
in television
television screens
screens and
and computer
computer monitors,
monitors, is
is driving
driving the
the
development
development of
of some
some nanomaterials.
nanomaterials.
Nanocrystalline zinc
Nanocrystalline
zinc selenide,
selenide, zine
zine sulphide,
sulphide, cadmium
cadmium sulphide
sulphide and
and
lead
lead telluride
telluride synthesized
synthesized by
by sol-gel
sol-gel techniques
techniques (a
(a process
process for
for making
making
ceramic
ceramic and
and glass
glass materials,
materials, involving
involving the
the transition
transition from
from aa liquid
liquid ‘sol’
‘sol’
phase to
to aa solid
solid ‘gel’
‘gel’ phase)
phase) are
are candidates
candidates for
for the
the next
next generation
generation of
of
phase
light-emitting
light-emitting phosphors.
phosphors. CNTs
CNTs are
are being
being investigated
investigated for
for low
low voltage
voltage
field-emission
field-emission displays;
displays; their
their strength,
strength, sharpness,
sharpness, conductivity
conductivity and
and
inertness
inertness make
make them
them potentially
potentially very
very efficient
efficient and
and long-lasting
long-lasting
A emitters.
ye
emitters.
b)
b)
Batteries
Batteries
With the
the growth
growth in
in portable
portable electronic
electronic equipment
equipment (mobile
(mobile phones,
phones,
(1)
(1) With
navigation devices,
navigation
devices, laptop
laptop computers,
computers, remote
remote sensors),
sensors), there
there is
is great
great
demandfor
demand
for lightweight,
lightweight, high-energy
high-energy density
density batteries.
batteries.
(2)
(2)
Nanocrystalline materials
Nanocrystalline
materials synthesized
synthesized by
by sol-gel
sol-gel techniques
techniques are
are
candidates
candidates for
for separator
separator plates
plates in
in batteries
batteries because
because of
of their
their foam-like
foam-like
(aerogel) structure,
(aerogel)
structure, which
which can
can hold
hold considerably
considerably more
more energy
energy than
than
conventional
conventional ones.
ve
VS
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
e«
6-27
6-27
Nanomateriais
Nanomaterials
This technology
This
technology invites
invites for
for future
future applications
applications like
like potable
potable water
water and
and
separation of
separation
of viruses
viruses and
and bacteria.
bacteria.
°°
Gold nanoparticles
Gold
nanoparticles are
are used
used for
for degradation
degradation of
of toilet
toilet odour.
odour. TiO»
TiO: isis used
used as
as aa
tunnellight
tunnel
light shield
shield coating
coating itit converts
converts deposited
deposited carbon
carbon to
to CO,
CO, thus
thus keeping
keeping
the shield
the
shield transparent.
transparent. Nano
Nano ZnO
ZnO isis used
used for
for degradation
degradation of
of chlorinated
chlorinated
phenols.
phenols.
°e
Futuristic
Futuristic
use
use
of aa
of
nanocoating
nanocoating
on
on
the
the
swimming pool
swimming
pool
walls
walls
by
by
photocatalytically active
photocatalytically
active material
material can
can lead
lead to
to activation
activation of
of oxygen,
oxygen, forr:ing
forn:ing
hydroxyl ions
hydroxyl
ions which
which are
are antibacterial
antibacterial (alkaline)
(alkaline) and
and also
also degrade
degrade organic
organic
compounds.
compounds.
e©
Nanobased sensors,
Nanobased
sensors, metal
metal sensors,
sensors, polymer
polymer sensors
sensors are
are used
used to
to analyse
analyse gas
gas
mixtures by
mixtures
by measuring
measuring solubility
solubility of
of gases,
gases, vapour
vapour pressure,
pressure, melting
melting point
point
etc. biegenseors
etc.
biosensors will
will be
be used
used in
in future
future as
as aa lab
lab on
on chin
chin by
by chemists,
chemists,
biochemists, physicians,
biochemists,
physicians, engineers
engineersetc.
etc.
e®
The potential
The
potential of
of nanoparticles
nanoparticles to
to react
react with
with pollutants
pollutants in
in soil
soil and
and
groundwater
groundwater and
and transform
transform them
them into
into harmless
harmless compounds
compounds isis being
being
researched.
researched.
ee
In one
In
one pilot
pilot study
study the
the large
large surface
surface area
area and
and high
high surface
surface reactivity
reactivity of
of iron
iron
nanoparticles were
nanoparticles
were exploited
exploited to
to transform
transform chlorinated
chlorinated hydrocarbons
hydrocarbons (some
(some of
of
which are
which
are believed
believed to
to be
be carcinogens)
carcinogens) into
into less
less harmful
harmful end
end products
products in
in
groundwater.
groundwater.
se
ItIt isis also
also hoped
hoped that
that they
they could
could be
be used
used to
to transform
transform heavy
heavy metals
metals such
such as
as
lead and
lead
and mercury
mercury from
from bioavailable
bioavailable forms
forms into
into insoluble
insoluble forms.
forms.
6.13.5
6.13.5Applications
Applications in
in Electronics
Electronics te
pee
fae
-(
eation
‘0
ation
bleehomics
Eleebrmies £
£ Telecormmunienr
Telecormmunienr
yyyD ray
ray 2008,
2008,
May
May 2010
2010 !]!]
To
To increase
increase the
the speed
speed at
at which
which electric
electric charges
charges work,
work, the
the distance
distance between
between
them needs
them
needs to
to be
be decreased.
decreased. Thus
Thus number
number of
of transistors
transistors per
per unit
unit area
area increases
increases
every year.
every
year. But
But there
there 1s
is aa limit
limit for
for this
this growth.
growth. AA time
time at
at which
which the
the space
spaceto
to store
store
one
one bit
bit becomes
becomes about
about 44 nm,
nm, the
the things
things happen
happen at
at quantum
quantum level
level heat
heat will
will be
be
developed,
developed, neighbourings
neighbourings bits
bits would
would interact.
interact.
-5
YS
v
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
6-28
6-28
Nanomaterials
Nanomaterials
At present
At
present atomic
atomic scale
scale memory
memory isis possible.
possible. AA bit
bit isis encoded
encoded by
by the
the pres/abs
pres/abs
of —Si
of
—Si atom
atom inside
inside 55 xx 44 == 20
20 atoms.
atoms. Thus
Thus 19
19 atoms
atoms prevent
prevent or
or absorb
absorb the
the heat
heat
energy. Thus
Thus storage
storage capacity
capacity of
of hard
hard disks
disks is
is increased.
Thin films
films of
organic
energy.
increased. Thin
of organic
materials emitting
materials
emitting light
light (OLED)
(OLED) are
are known.
known. Thin
Thin film
film transistors
transistors TFT
TFT and
and thin
thin
film organic
film
organic photovoltaic
photovoltaic cells
cells are
are known.
known.
The deposition
The
deposition at
at aa reasonable
reasonable cost
cost isis possible
possible because
because of
of organo
organo inorganic
inorganic
metallic compounds
metallic
compounds which
which are
are normally
normally the
the self
self assembeled,
assembeled, nanomaterials.
nanomaterials. They
They
‘can form
‘can
form thin
thin films
films by
by simple
simple techniques
techniques the
the spray,
spray, spin
spin cooling
cooling vapour
vapour
deposition,
deposition, inkjet
inkjet printingetc.
printing ete.
a),
a),
v2
Displays
Displays
(1)
(1)
The
The huge
huge market
market for
for large
large area,
area, high
high brightness,
brightness, flat-panel
flat-panel displays,
displays, as
as
used
used in
in television
television screens
screens and
and computer
computer monitors,
monitors, is
is driving
driving the
the
development
development of
of some
some nanomaterials.
nanomaterials.
(2)
(2)
Nanocrystalline
Nanocrystalline zine
zine selenide,
selenide, zine
zine sulphide,
sulphide, cadmium
cadmium sulphide
sulphide and
and
|
lead telluride
telluride synthesized
synthesized by
by sol-gel
sol—gel techniques
(a process
for making
making
lead
techniques (a
process for
ceramic and
ceramic
and glass
glass materials,
materials, involving
involving the
the transition
transition from
from aa liquid
liquid ‘sol’
‘sol’
phase to
phase
to aa solid
solid ‘gel’
‘gel’ phase)
phase) are
are candidates
candidates for
for the
the next
next generation
generation of
of
light-emitting phosphors.
light-emitting
phosphors. CNTs
CNTs are
are being
being investigated
investigated for
for low
low voltage
voltage
jield-emission
jield-emission displays;
displays; their
their strength,
strength, sharpness,
sharpness, conductivity
conductivity and
and
inertness make
very efficient
efficient and
long-lasting
inertness
make them
them potentially
potentially very
and long-lasting
.oe
A emitters.
emitters.
b)
b)
Batteries
Batteries
(1)
(1)
With the
With
the growth
growth in
in portable
portable electronic
electronic equipment
equipment (mobile
(mobile phones,
phones,
navigation
great
navigation devices,
devices, laptop
laptop computers,
computers, remote
remote sensors),
sensors), there
there isis great
demandfor
demand
for lightweight,
lightweight, high-energy
high-energy density
density batteries.
batteries.
(2)
(2)
Nanocrystalline materials
Nanocrystalline
materials synthesized
synthesized by
by sol-gel
sol-gel techniques
techniques are
are
candidates
candidates for
for separator
separator plates
plates in
in batteries
batteries because
because of
of their
their foam-like
foam-like
(aerogel)
(aerogel) structure,
structure, which
which can
can hold
hold considerably
considerably more
more energy
energy than
than
conventional ones.
conventional
ones.
eee
oa
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
(3)
(3)
6-29
6-29
Nanomaterials
Nanomaterials
Nickel-metal hydride
Nickel-metal
hydride batteries
batteries made
made of
of nanocrystalline
nanocrystalline nickel
nickel and
and
metal hydrides
metal
hydrides are
are envisioned
envisioned to
to require
require less
less frequent
frequent recharging
recharging and
and
to last
to
last longer
longer because
becauseof
of their
their large
large grain
grain boundary
boundary (surface)
(surface) area.
area.
c)
c)
Magnetic Materials
Magnetic
Materials X
X
(1)
(1)
It has
It
has been
been shown
shown that
that magnets
magnets made
made of
of nanocrystalline
nanocrystalline yttrium-—
yttrium-—
samarium-—cobalt grains
grains possess
possess unusual
unusual magnetic
magnetic properties
properties due
due to
to
samarium—cobalt
their extremely
their
extremely large
large grain
grain interface
interface area
area (high
(high coercivity
coercivity can
can be
be
obtained because
obtained
because magnetization
magnetization flips
flips cannot
cannot easily
easily propagate
propagate past
past the
the
grain boundaries).
grain
boundaries). This
This could
could lead
lead to
to applications
applications in
in motors,
motors, analytical
analytical
instruments like
instruments
like magnetic
magnetic resonance
resonance imaging
imaging (MRI),
(MRI), used
used widely
widely in
in
hospitals,
hospitals, and
and microsensors.
microsensors.
(2)
(2)
Overall magnetisation,
Overall
magnetisation, however,
however, isis currently
currently limited
limited by
by the
the ability
ability to
to
align the
align
the grains’
grains’ direction
direction of
of magnetisation.
magnetisation.
Nanoscale-fabricated magnetic
magnetic materials
materials also
also have
have applications
applications in
in
(3)
(3) Nanoscale-fabricated
data storage.
data
storage.
(4)
(4)
Devices such
Devices
such as
as computer
computer hard
hard disks
disks depend
depend on
on the
the ability
ability to
to
magnetize small
magnetize
small areas
areas of
of aa spinning
spinning disk
disk to
to record
record information.
information. If
If the
the
area required
area
required to
to record
record one
one piece
piece of
of information
information can
can be
be shrunk
shrunk in
in the
the
nanoscale (and
nanoscale
(and can
can be
be written
written and
and read
read reliably),
reliably), the
the storage
storage capacity
capacity
of
of the
the disk
disk can
can be
be improved
improved dramatically.
dramatically. In
In the
the future,
future, the
the devices
devices on
on
computer
computer chips
chips which
which currently
currently operate
operate using
using flows
flows of
of electrons
electrons could
could
use
use the
the magnetic
magnetic properties
properties of
of these
these electrons,
electrons, called
called spin,
spin, with
with
numerous advantages.
numerous
advantages.
(5)
(5)
Recent
Recent advances
advances in
in novel
novel magnetic
magnetic materials
materials and
and their
their nanofabrication
nanofabrication
are encouraging
are
encouraging in
in this
this respect.
6.13.6
6.13.6
Nanomaterials
Nanomaterials
6-30
6-30
(MU)
Chemistry -- | (MU)
Applied Chemistry
Applied
General
Applications
General Applications
»
» [[ May
May 2010!
2010 ! ]
b)
b)
Composites
Composites
a)
a)
Clays
Clays
ce)
ce)
Surfaces
and Surfaces
Coatings
Coatings and
e)
e)
Paints
Paints
f)
f)
Fuel
Cells
Fuel Cells
g)
g)
Fuel
Additives
Fuel Additives
h)
h)
Composites
Nanotube Composites
Carbon
Carbon Nanotube
i)
i)
Ceramics
Ceramics
j)
j)
Purification
Water
Water Purification
(1)
(1)
d)
' d)
:
i
Cosmetics
and Cosmetics
Sunscreens
Sunscreens and
been
long been
have long
nanoparticles have
occurring nanoparticles
naturally occurring
containing naturally
Clays containing
Clays
continuous
undergoing continuous
are undergoing
and are
materials and
construction materials
as construction
important
important as
improvement.
improvement.
nano-sized
and nano-sized
plastics and
containing plastics
— containing
composites —
(2)
based composites
particle based
Clay particle
(2) Clay
car
in car
use in
as use
such as
applications such
finding applications
also finding
are also
— are
clay —
of clay
flakes of
flakes
bumpers.
bumpers.
b)
b})
Composites
Compasites
(1)
(1)
composites,
in composites,
is in
nanotubes is
and nanotubes
An important
important use
use of
of nanoparticles
nanoparticles and
An
which
and which
components and
separate components
more separate
or more
one or
combine one
materials
that combine
materials that
component.
each component.
of each
properties of
best properties
the best
overall the
exhibit overall
to exhibit
designed to
are designed
are
(2)
(2)
but
properties, but
mechanical properties,
to mechanical
only to
not only
applies not
ity applies
This
multi-functionality
This multi-functional
carbon
Currently, carbon
ones. Currently,
magnetic ones.
and magnetic
electrical and
optical, electrical
to optical,
extends to
extends
to
polymers to
in polymers
used in
are used
CNTs are
multi-walled CNTs
of multi-walled
bundles of
and bundles
fibres
fibres and
as antistatic
antistatic
such as
applications such
or enhance
control
with applications
conductivity, with
enhance conductivity,
control or
packaging.
packaging.
(3)
(3)
long-term
potential long-term
composites isis aa potential
in composites
CNTs in
individual CNTs
of individual
use of
The use
The
nanoparticles
where nanoparticles
application.
nanocomposite isis where
of nanocomposite
type of
particular type
application. AA particular
to
filler to
asa a filler
used as
black used
carbon black
example, carbon
act
for example,
matrix; for
in aa matrix;
fillers in
as fillers
act as
from
range from
can range
black can
carbon black
of carbon
particles of
However, particles
tyres. However,
car tyres.
reinforce car
reinforce
falls //
black falls
carbon black
all carbon
not all
so not
tens
size, so
in size,
nanometres in
of nanometres
hundreds of
to hundreds
tens to
within
nanoparticles.
of nanoparticles.
definition of
our definition
within our
=
—_
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
c)
c)
6-31
6-31
Nanomaterials
Nanomaterials
Coatings and
Coatings
and Surfaces
Surfaces
(1)
(1)
Coatings with
Coatings
with thickness
thickness controlled
controlled at
at the
the nanonano- or
or atomic
atomic scale
scale have
have
been in
been
in routine
routine production
production for
for some
some time,
time, for
for example
example in
in molecular
molecular
beam.
beam epitaxy
epitaxy or
or metal
metal oxide
oxide chemical
chemical vapor
vapor depositionfor
depositionfor optoelectonic
optoelectonic
devices, or
devices,
or in
in catalytically
catalytically active
active and
and chemically
chemically functionalized
functionalized
surfaces.
surfaces.
(2)
(2)
Recently developed
Recently
developed applications
applications include
include the
the self-cleaning
self-cleaning window,
window,
which isis coated
which
coated in
in highly
highly activated
activated titanium
titanium dioxide,
dioxide, engineered
engineered to
to be
be
highly hydrophobic
highly
hydrophobic (water
(water repellent)
repellent) and
and antibacterial,
antibacterial, and
and coatings
coatings
based on
based
on nanoparticulate
nanoparticulate oxides
oxides that
that catalytically
catalytically destroy
destroy chemical
chemical
agents.
agents.
“Wear and
and scratch-resistant
scratch-resistant hard
hard coatings
coatings are
are significantly
significantly improved
improved by
by
(3) “Wear
(3)
nanoscale intermediate
nanoscale
intermediate layers
layers (or
(or multilayers)
multilayers) between
between the
the hard
hard outer
outer
layer and
layer
and the
the substrate
substrate material,
material. The
The intermediate
intermediate layers
layers give
give good
good
bonding and
bonding
and graded
graded matching
matching of
of elastic
elastic and
and thermal
thermal properties,
properties, thus
thus
improving adhesion.
improving
adhesion.
range of
of enhanced
enhanced textiles,
textiles, such
such as
as breathable,
breathable, waterproof
waterproof and
and
(4) AA range
(4)
stainresistant fabrics,
stainresistant
fabrics, have
have been
been enabled
enabled by
by the
the improved
improved control
control of
of
porosity at
porosity
at the
the nanoscale
nanoscale and
and surface
surface roughness
roughness in
in aa variety
variety of
of
polymers and
polymers
and inorganics.
inorganics.
d)
d)
Sunscreens and
Sunscreens
and Cosmetics
Cosmetics
(1)
(1)
Nanosized
Nanosized titanium
titanium dioxide
dioxide and
and zinc
zinc oxide
oxide are
are currently
currently used
used in
in some
some
sunscreens,
sunscreens, as
as they
they adsorb
absorb and
and reflect
reflect ultraviolet
ultraviolet (UV)
(UV) rays
rays and
and yet
yet are
are
transparent to
transparent
to visible
visible light
light and
and s0
s0 are
are more
more appealing
appealing to
to the
the consumer.
consumer.
Nanosized iron
iron oxide
oxide isis present
present in
in some
somelipsticks
lipsticks as
as aa pigment
pigment but
but itit isis
(2) Nanosized
(2)
our understanding
our
understanding that
thatit
it isis not
not used
used by
by the
the European
European cosmetics
cosmetics sector.
sector.
The use
use of
of nanoparticles
nanoparticles in
in cosmetics
cosmetics has
has raised
raised aa number
number of
of concerns
concerns
(3) The
(3)
about consumer
about
consumersafety.
safety.
ee r
r
aaa
r
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
e)
e)
6-32
6-32
.,
Nanomaterials
Nanomaterials
Paints
Paints
(1)
(1)
Incorporating
could improve
improve their
Incorporating nanoparticles
nanoparticles in
in paints
paints could
their performance,
performance,
for
for example
example by
by making
making them
them lighter
lighter and
and giving
giving them
them different
different
properties.
properties. Thinner
Thinner paint
paint coatings
coatings (‘lightweighting’),
(‘lightweighting’), used
used for
for example
example
on
on aircraft,
aircraft, would
would reduce
reduce their
their weight,
weight, which
which could
could be
be beneficial
beneficial to
to the
the
environment.
environment. However,
However, the
the whole
whole life
life cycle
cycle of
of the
the aircraft
aircraft needs
needs to
to be
be
considered before
considered
before overall
overall benefits
benefits can
can be
be claimed.
claimed.
(2)
(2)
It may
It
may also
also be
be possible
possible to
to substantially
substantially reduce
reduce solvent
solvent content
content of
of paints,
paints,
with resulting
with
resulting environmental
environmental benefits.
benefits.
New types
types of
of foulingresistant
foulingresistant marine
marine paint
paint could
could be
be developed
developed and
and are
are
(3) New
(3)
urgently needed
urgently
needed as
as alternatives
alternatives to
to tributyl
tributyl tin
tin (TBT),
(TBT), now
now that
that the
the
ecological impacts
impacts of
of TBT
TBT have
been recognised.
recognised.
ecological
have been
Anti-fouling surface
surface treatment
treatment isis also
also valuable
valuable in
in process
process applications
applications
4) . Anti-fouling
((4).
such as
such
as heat
heat exchange,
exchange, where
where itit could
could lead
lead to
to energy
energy savings.
savings. If
If they
they
can be
can
be produced
produced at
at sufficiently
sufficiently low
low cost,
cost, fouling-resistant
fouling-resistant coatings
coatings
could be
could
be used
used in
in routine
routine duties
duties such
such as
as piping
piping for
for domestic
domestic and
and
industrial water
industrial
water systems.
systems.
(5)
(5)
remains speculation
speculation whether
whether very
very effective
effective anti-fouling
anti-fouling coatings
coatings
ItIt remains
could reduce
could
reduce the
the use
use of
of biocides,
biocides, including
including chlorine,
chlorine, Other
Other novel,
novel, and
and
more long-term,
more
long-term, applications
applications for
for nanoparticles
nanoparticles might
might lie
lie in
in paints
paints that
that
change colour
colour in
in response
change in
in temperature
temperature or
or chemical
change
response to
to change
chemical
environment,
environment, or
or paints
paints that
that have
have reduced
reduced infra-red
infra-red absorptivity
absorptivity and
and so
so
reduce heat
reduce
heatloss.
loss.
(6)
(6)
Concerns about
Concerns
about the
the health
health and
and environmental
environmental impacts
impacts of
of nanoparticles
nanoparticles
may require
may
require the
the need
need for
for the
the durability
durability and
and abrasion
abrasion behaviour
behaviour of
of
nano-engineered
nano-engineered paints
paints and
and coatings
coatings to
to be
be addressed,
addressed, so
so that
that abrasion
abrasion
products
products take
take the
the form
form of
of coarse
coarse or
or microscopic
microscopic agglomerates
agglomerates rather
rather
than
than individual
individual nanoparticles.
Applied Chemistry
Applied
Chemistry -- | (MU)
(MU)
f)
f)
6-33
6-33
Nanomaterials
Nanomaterials
Fuel Cells
Fuel
Cells
Engineered surfaces
surfaces are
are essential
essential in
in fuel
fuel cells,
cells, where
where the
the external
external
(1) Engineered
(1)
surface properties
surface
properties and
and the
the pore
pore structure
structure affect
affect performance.
performance.
(2)
(2)
The hydrogen
The
hydrogen used
used asas the
the immediate
immediate fuel
fuel inin fuel
fuel cells
cells may
may bebe
generated from
generated
from hydrocarbons
hydrocarbons by
by catalytic
catalytic reforming,
reforming, usually
usually in
in aa
reactor module
reactor
module associated
associated directly
directly with
with the
the fuel
fuel cell.
cell.
(3)
(3)
The potential
The
potential use
use of
of nano-engineered
nano-engineered membranes
membranes to
to intensify
intensify catalytic
catalytic
processes could
processes
could enable
enable higher-efficiency,
higher-efficiency, small-scale
small-scale fuel
fuel cells.
cells. These
These
could act
could
act as
as distributed
distributed sources
sources of
of electrical
electrical power.
power.
(4)
(4)
It may
It
may eventually
eventually be
be possible
possible to
to produce
produce hydrogen
hydrogen locally
locally from
from sources
sources
other than
other
than hydrocarbons,
hydrocarbons, which
which are
are the
the feedstocks
feedstocks of
of current
current attention.
attention.
g) Fuel
g)
Fuel Additives
Additives
Research isis underway
Research
underway into
into the
the addition
addition of
of nanoparticulate
nanoparticulate ceria
ceria (cerium
(cerium
oxide) to
oxide)
to diesel
diesel fuel
fuel to
to improve
improve fuel
fuel economy
economy by
by reducing
reducing the
the degradation
degradation of
of fuel
fuel
consumption over
consumption
overtime.
time.
h)
h)
Carbon Nanotube
Carbon
Nanotube Composites
Composites
(1)
(1)
CNTs have
CNTs
have exceptional
exceptional mechanical
mechanical properties,
properties, particularly
particularly high
high tensile
tensile
strength and
strength
and light
light weight.
weight. An
An obvious
obvious area
area of
of application
application would
would be
be in
in
nanotubereinforced composites,
nanotubereinforced
composites,
with performance
with
performance beyond
beyond current
current
carbon-fibre composites.
carbon-fibre
composites.
One current
current limit
limit to
to the
the introduction
introduction of
of CNTs
CNTs in
in composites
composites isis the
the
(2) One
(2)
problem of
problem
of structuring
structuring the
the tangle
tangle of
of nanotubes
nanotubes in
in aa well-ordered
well-ordered
manner so
manner
so that
that use
use can
can be
be made
made of
of their
their strength.
strength. Another
Another challenge
challenge isis
generating strong
generating
strong bonding
bonding between
between CNTs
CNTs and
and the
the matrix,
matrix, to
to give
give good
good
overall composite
overall
composite performance
performance and
and retention
retention during
during wear
wear or
or erosion
erosion of
of
composites.
composites.
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
(3)
(3)
6-34
6-34
Nanomaterials
Nanomaterials
The
The surfaces
surfaces of
of CNTs
CNTs are
are smooth
smooth and
and relatively
relatively unreactive,
unreactive, and
and so
so tend
tend
to slip
slip through
through the
the matrix
matrix when
whenit
stressed.
to
it isis stressed.
(4)
(4)
One approach
approach that
that isis being
being explored
explored to
to prevent
prevent this
this slippage
slippage isis the
the
One
attachment
attachment of
of chemical
chemical side-groups
side-groups to
to CNTs,
CNTs, effectively
effectively to
to form
form
‘anchors.
‘anchors’.
(5)
(5)
Another limiting
Another
limiting factor
factor isis the
the cost
cost of
of production
production of
of CNTs.
CNTs. However,
However, the
the
potential
potential benefits
benefits of
of such
such light,
light, high
high strength
strength material
material in
in numerous
numerous
applications
applications for
for transportation
transportation are
are such
such that
that significant
significant further
further
researchis
research
is likely.
likely.
i)i)
Ceramics
Ceramics
(1)
(1)
Ceramics
Ceramics are
are hard,
hard, brittle
brittle and
and difficult
difficult to
to machine.
machine. However,
However, with
with a
a
reduction
reduction in
in grain
grain size
size to
to the
the nanoscale,
nanoscale, ceramic
ceramic ductility
ductility can
can be
be
increased.
increased. Zirconia,
Zirconia, normally
normally a
a hard,
hard, brittle
brittle ceramic,
ceramic, hag
hag even
even been
been
rendered
rendered superplastic
superplastic (for
(for example,
example, able
able to
to be
be deformed
deformed up
up te
to 300%
300% of
of
its
its original
original length).
length).
(2)
(2)
Nanocrystalline ceramics,
ceramics, such
such as
as silicon
silicon nitride
nitride and
and silicon
silicon carbide,
Nanocrystalline
carbide,
have been
been used
used in
in such
such automotive
automotive applications
applications as
high-strength
have
as high-strength
springs,
ball bearings
valve lifters,
lifters, because
because they
they can
can be
be easily
springs, ball
bearings and
and valve
easily
formed and
formed
and machined,
machined, as
as well
well as
as exhibiting
exhibiting excellent
excellent chemical
chemical and
and
high-temperature
high-temperature properties.
properties. They
They are
are also
also used
used as
as components
components in
in
high-temperature furnaces.
furnaces. Nanocrystalline
Nanocrystalline ceramica
can be
be preased
preased
high-temperature
ceramica can
into
into
complex
complex net
net
shapes
shapes
and
and
sintered
sintered
at
at
significantly
significantly
lower
lower
temperatures
temperatures than
than conventional
conventional ceramics.
ceramics.
j)
j)
Water
Water Purification
Purification
(1)
(1)
Nano-engineered membranes
membranes could
could potentially
potentially lead
lead to
to more
more energyenergyNano-engineered
efficient water
water purification
purification processes,
processes, notably
notably in
in desalination
desalination by
by reverse
reverse
efficient
osmosis.
osmosis.
Applied
Applied Chemistry
Chemistry -- | (MU)
(MU)
6-35
6-35
a
nee
Nanomaterials
Nanomaterials
Again, these
these applications
applications would
would represent
represent incremental
incremental improvements
improvements
(2) Again,
(2)
in technologies
technologies that
that are
are already
already available.
available. They
would use
use fixed
fixed
in
They would
nanoparticles,
nanoparticles, and
and are
are therefore
therefore distinct
distinct from
from applications
applications that
that propose
propose
to use
to
use free
free nanoparticles.
nanoparticles.
k)
k)
Military Battle
Battle Suits
Suits
Military
(1)
(1)
Enhanced
Enhanced nanomaterials
nanomaterials form
form the
the basis
basis of
of aa state-ofstate-of- the-art
the-art ‘battle
battle
suit?’
suit?
that
that
isis
being
being
developed
developed
by
by
the
the
Institute
Institute
of
of
Soldier
Soldier
Nanotechnologies
Nanotechnologies at
at MIT.
MIT.
short-term development
development isis likely
likely to
to be
be energy-absorbing
energy-absorbing materials
materials
(2) AA short-term
(2)
that
that will
will withstand
withstand blast
blast waves;
waves; longer-term
longer-term are
are those
those that
that incorporate
incorporate
sensors
sensors to
to detect
detect or
or respond
respond to
to chemical
chemical and
and biological
biological weapons
weapons (for
(for
example, responsive
example,
responsive nanopores
nanopores that
that ‘close’
‘close’ upon
upon detection
detection of
of aa
- biological
biological agent).
agent).
is speculation
developments could
could include
include materials
materials which
which
There is
speculation that
that developments
(3) There
(3)
monitor physiology
physiology while
while aa soldier
is still
still on
the battlefield,
battlefield, and
monitor
soldier is
on the
and
uniforms with
uniforms
with potential
potential medical
medical applications,
applications, such
such as
as splints
splints for
for broken
broken
bones.
bones.
O72
Q..2
State the
State
the size
size of
of HH atom,
atom, Cg,
Cg, ¢c nanotubes,
nanotubes, DNA
DNA molecule
molecule etc.
etc. on
on
nanometerscale.
nanometer
scale.
Why the
Why
the properties
properties of
of nanomaterials
nanomaterials are
are different
different than
than the
the conventional
conventional
materials.
materials.
on
OO
wT
on
oO
wm
2POaHLO
S822 2 2
O©
Define
Define nanomaterials.
nanomaterials.
ALP
Q.1
Oak
Ww
Ww
Review
Review Questions
Questions
State
State the
the structural
structural details
details of
of graphene.
graphene.
State the
State
the structura!
structural! details
details of
of graphite.
graphite.
State the
the structural
fullerene.
State
structural details
details of
of fullerene.
What
What are
are carbon
carbon nanotubes
nanotubes whatare
what are their
their types.
types.
List the
List
the methods
methods for
for production
production of
of carbon
carbon nanotubes.
nanotubes.
6-36
6-36
(MU)
Chemistry -- | (MU)
Applied Chemistry
Applied
Q.9
Q.9
Nanomaterials
Nanomaterials
the
with the
carbonanotubes with
of carbonanotubes
preparation of
the preparation
for the
method for
one method
any one
Explain any
Explain
methods.
other methods.
the other
over the
method over
this method
of this
limitations of
and limitations
of and
advantages of
advantages
their applications?
applications?
are their
whatare
and what
made and
they made
are they
how are
nanomines, how
are nanomines,
What are
10 What
Q. 10
Q.
Describe
materials? Describe
interesting materials?
are interesting
haecklites are
and haecklites
nanocones and
why nanocones
and why
How and
11 How
Q.
Q. 11
structures.
their structures.
their
Q.
Q. 12
12 Explain
Explain the
the use
use of
of nanomaterials
nanomaterials inin
(i)
(i)
Medecine
Medecine
(ii)
(ii)
Electronics
Electronics
(iii)
(iii)
Environment
Environment pollution
pollution control
control
(iv)
(iv) Mechanics
Mechanics
(Theory) ||
Questionss (Theory)
Universityy Question
6.14 Universit
|| 6.14
—s
“De
“Beec..2200007.7
Q.Q. 11
6.4)
(Section 6.4)
fullerene. (Section
of fullerene.
usesof
and uses
properties and
structure, properties
the structure,
Explain
Explain the
Marks)
(2 Marks)
(2
Q.22
Q.
SWCNT
of SWCNT
production of
the production
Describe the
MWCNT ?? Describe
(ii) MWCNT
and (ii)
SWCNT and
(i) SWCNT
are (i)
What are
What
6.7.2)
(Section 6.7.2)
method. (Section
LASER method.
by LASER
by
Q.3
Q.3
Marks)
(6 Marks)
(6
Write short
Write
short notes
notes on,
on, any
any two
two the
the following
following :
(i)
(i)
Nanocones
Nanocones (Section
(Section 6.11)
6.11)
6.12)
(Section 6.12)
(ii)
Haeckelites (Section
(ii) Haeckelites
Marks)
(6
(6 Marks)
“May
2008 “May2008
Q. 11
Q.
s.
carbon-nanotubees.
of carbon-nanotub
types of
different types
Explain different
s ?? Explain
carbon-nanotubees
are carbon-nanotub
What are
What
6.6)
(Section
(Section 6.6)
2.
Q. 2.
Q.
Marks)
(2
(2 Marks)
following :
the following
of the
two of
any two
of any
filed of
the filed
in the
materials in
nano materials
of nano
use of
the use
Explain the
Explain
(i)
(i)
Medicine (Section
Medicine
(Section 6.13.2)
6.13.2)
(ii)
(ii) Electronics
Electronics (Section
(Section 6.13.5)
6.13.5)
6.13.3)
(Section 6.13.3)
Catalysis (Section
(iii)
(iii) Catalysis
Marks)
(6 Marks)
(6