Nanomaterials

Introduction to Nanomaterials
Historical background
● Nobel Prize winner Richard Feynman said in 1959in
conference, «The principlesof physics, as faras I can
see, do not speak against the possibility of
manoeuvring things atom byatom»
● Theword « nanotechnology » was first used by Norio
Taniguchi in 1974 to refer to precise and accurate
tolerance required for machining and finishing of
materials
● In 1981, Drexlerdescribea new « bottomup »
technique instead of « top down»
● The term nanoderives from the Greek word fordwarf
● A nanometer (nm) is a billionthof a meter, or 10−9
meters.

Introduction

Introduction
What arenanomaterials?
● The materials having at leastone dimensions in
nanometric scale are callednanomaterials
● Nanotechnology is the understanding and control of
matteratdimensions of roughly 1 to 100 nanometers, where
unique phenomena enable novelapplications
● Encompassing nanoscale science, engineering and
technology, nanotechnology involves imaging, measuring,
modeling, and manipulating matter at this lengthscale.”
● The term is reallyan “umbrella term” thatcovers
disciplines that haveveryold historicroots.

Introduction
What is sospecial about nanotechnology?
● First, it is an incredibly broad, interdisciplinaryfield.
● It requires expertise in physics, chemistry, materials
science, biology, mechanical and electrical
engineering, medicine, and their collectiveknowledge.
● The boundary between atomsand moleculesand the
macroworld.

● Particles having sizes in the range of 1 to 100 nm are
termed as nanoparticles and the applicationof nano-
sized particles is what we call‘nanotechnology’.
6

What is special innanomaterials?
● At the nanoscale, the physical, chemical, and biological
propertiesof materialsdiffer in fundamental and valuable
ways from the properties of individual atoms and
molecules or bulkmatter.
● With the reduction in size, the surface areaof materials
and surface energy increasetremendously.
7

Types of nanostructures
●

Introduction
Approaches to nanomaterialssynthesis
Twoapproaches areused:
● Topdownapproach
● Bottom upapproach

Introduction
TopdownApproach
● Generally, a bulk material is taken and machinedand
modify toobtain required sizeand shape
● Theexampleof thisapproach is the production of
integrated circuits by etching orlithography

Introduction
TopdownApproach
● For nanomaterials synthesis, ball milling isused
● Macrocrystalline structures are broken downto
nanocrystallinestructures.

Introduction
Bottom upApproach
● It is used to build from basic material, forexample,
assembling materials fromatom/molecules
● The commonly used methods include sol-gel,
hydrothermal, physical and chemical vapordeposition,
epitaxialgrowth

Introduction
● Topdown vs bottomup

Introduction
Nanomaterials in Nature
● The nature is the best manufucturerof nanomaterials
and nanostructures
● By natural nanomaterials means, the materials that
belong to the natural world (plants, animal and
mineral), without human modification orprocessing
● Due to their structures, they have remarkable
properties because of their inherentnanostructure.

Introduction
● Butterflies

Introduction
● Why butterflies have differentcolors?

● Introduction
● Mimicking butterflies’colors

Introduction
● Mimicking butterflies’colors
Cadmium selenidenanoparticles
Silvernanoparticles

● Introduction
● Antibacterial properties of Cicadawings

Introduction
● Mimicking antibacterial properties of Cicadawings

Introduction
● Lotus leaf----> self-cleaningeffect
α <5°
θ > 150°
21
θ
α
Analysis of Lotus leaf
Hierarchical roughness
structure

Introduction
● Gecko feet

Introduction
Nanomaterials in arts andcultural heritage
● Stained-glasswindows
● Made of acomposite of glass and nano-sized metal
particles
● The “ruby-red” glasses often seen area mixtureof glass
with ultrafine (nanosized) goldpowder

Introduction
Nanomaterials in arts andcultural heritage
● The Lycurguscup, dating from the fifth century
Illuminated from the inside Illuminated from theoutside
● Due to the presence of nanosized particles of silver (66.2%), gold
(31.2%) and copper (2.6%), up to 100 nm in size, thatwereembedded in
theglass
● Lightabsorptionand scattering by these nanoparticlesdetermines the
differentcolours

Introduction
Application of nanomaterials
Paints
● Incorporating nanoparticles in paints couldimprove
theirperformance
● Itcan impartvarious functional properties like self-
cleaning.

Introduction
● Sunscreens and Cosmetics
● The traditional chemical UV protection approachsuffers
from its poor long-termstability
● Nanosized titaniumdioxideand zincoxide arecurrently
used in some sunscreens, as they absorb and reflect
ultraviolet (UV)rays.
● Transparent tovisible lightand so are moreappealing to
theconsumer.
● Nanosized iron oxide is present in some lipsticksas a
pigment.

Introduction
Effluenttreatment
● Nanophotocatalystsare much moreefficient than
micro and macrophotocatalysts.
● Theydegrade the toxiccolorantsand otherorganic
species

Introduction
Medicine
● Nanotechnology has beena boon in medical field by
delivering drugs to specificcells using nanoparticles.
● Theoverall drug consumptionand sideeffectscan be
lowered significantly by depositing the agent in the
morbid region only and in no higher dose than
needed.

Introduction
Sensors forgases
● Sensorsemploy theirsensitivity to thechanges in various
parameterstheyaredesigned to measure.
● The measured parameters includeelectrical resistivity, chemical
activity, magnetic permeability, thermal conductivity, and
capacitance
● acarbon monoxidesensormadeof zirconium oxide (zirconia)
uses its chemical stability to detect the presence of carbon
monoxide.
● Theoxygenatoms in zirconiumoxide reactwith thecarbon in
carbon monoxide to partially reduce zirconiumoxide.
● This reaction triggersachange in the sensor’scharacteristics,
such asconductivity
● Thegases like NO 2 and NH 3 can bedetected on the basis of
increase in electrical conductivity ofnanomaterials.

Introduction
Food
● Nanotechnologycan beapplied in the production,
processing, safety and packaging of food.
● A nanocomposite coating process could improve food
packaging by placing anti-microbial agents directlyon
the surface of thecoated film.

Introduction
Construction
● Nanotechnology has the potential tomake
construction faster, cheaper andsafer.
● The Silica (SiO 2 ) is present in conventionalconcrete
as part of the normalmix
● When nanosilica is added toconcrete the particle
packing can be improved mechanicalproperties.
● The nanosize steel producestrongersteel cables
which can be used in bridgeconstruction.
● NanoTiO2 coated glass have properties of anti-fouling
and glaze.

Introduction
Energy
● Nanomaterials have thecapacity tostore hugeamount
of energy.
● Today’ssolarcells use multiple layers of different
semiconductors in nanometricrange
● Theyare much moreefficient than theone 20 years.

Introduction
Better InsulationMaterials
● Nanocrystalline materials synthesised by thesol-gel
technique result in foam like structures called
"aerogels.“
● These aerogelsare porousand extremely lightweight
● Aerogels are composed of three-dimensional,
continuous networksof particleswith air trapped at
their interstices.

Introduction
Tougherand Harder CuttingTools
● Cutting tools made of nanocrystalline materials,such
as tungsten carbide, tantalum carbide, and titanium
carbide, are much harder, much more wear-resistant,
erosion-resistant.
● These tools are required formicroelectronics

Introduction
High-PowerMagnets
● The magnetic powerdependson the specific surface
area
● The magnets made of nanocrystalline grainspossess
very unusual magnetic properties due to their
extremely large surfacearea
● They are used in ultra-sensitiveanalytical instruments,
and magnetic resonance imaging (MRI) in medical
diagnostics.
● Motors forships

Introduction
Enhanced performance ofcomponents
● The fatiguestrength is an important parameterthat
determines the component’slife
● The fatiguestrength increases with a reduction in the
grain size of thematerial.
● By using nanomaterials, the fatiguestrengthcan be
increased by an average of 200-300%.

● Introduction

Nanomaterials

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