sri pushpam nano-new,gcm,ppt

8/8/2019 Sri Pushpam Nano-new,GCM,PPT

http://slidepdf.com/reader/full/sri-pushpam-nano-newgcmppt 1/48

³³Principles of Principles of NanoNano ChemistryChemistryandand NanoNano TechnologyTechnology´́

Associate ProfessorAssociate Professor in Chemistryin ChemistryP.G. and Research Department of P.G. and Research Department of

ChemistryChemistryA.V.V.M SriA.V.V.M Sri PushpamPushpam College,College, PoondiPoondi,,

ThanjavurThanjavur DtDt,,



there is an important message here for all of

us to nurture young talent for all scientific

research work, particularly in nanoscience and

nanotechnology. With 540 million youth inIndia, we have to hone skills of youth at the

graduate, post-graduate and Ph.D levels, " Mr.

Kalam said.



- He rued that despite doing exceedinglywell in the field of research in advanced

topics right from the late 1950s, Indialagged behind in implementing the

research findings on a commercial level.

"This should not happen vis-à-vis areas like

nanotechnology ..



History

China- 1000 years ago ± gold nano

particles as inorganic dye to

introduce red color in ceramic

porcelains

Faraday ±1857- electrolysis ± gold

nano particles ± colloid.



Contd

Colloidal gold was and is still used for medical

treatment of arthritis.

Number of diseases were diagnosed by

sending colloidal gold with the spinal liquid.



Diffrence between nano and bulk?

Nano ± Particles of size between 1nm to 50

nm

Bulk ± Particles of size larger than 60nm



Nano-science & Nano-technologyNanoscience is actually Materials Science at atomic level.

Nano-technology is Controlled manufacturing and

characterization of materials with predetermined and artificially

modified atomic and molecular structure.

To accomplish that one needs to manipulate with atoms and

molecules at nanoscale.

The word ³nano´ relates to the dimension scale comparable

with 1 nm = 10-9m.

Typical size of nano-objects ranges from 1 to 100 nm



Less than a

nanometer

Individualatoms are up

to a few tenths

of a nanometer

in diameter

Nanometer

Ten shoulder-

to-shoulder hydrogen

atoms (blue

balls) span 1

nanometer.

DNA

molecules are

about 2.5nm

wide

Thousands of

nanometers

Biologicalcells, like

these red

blood cells,

have

diameters in

the range of

thousands of

nanometers

A million

nanometers

An ant ismillions of

nanometers

across

Billions of

nanometers

A two meter tall male is two

billion

nanometers

tall



Characteristics of Nanoscalar materials: <L> <<100nm!

Size : 10-9m

Area : 10-18 m2

Volume : 10-27 m3

Mass : 10-24kg

Specific surface area : 106 m2/kg

% of chemical bonding sites on the surface : 20-50

Large Gibbs Free Energy : Ease of sintering/

Ease of dissolution

Surface forces and Brownian motion become increasingly

significant

You cannot see or touch discrete nanoscalar materials



Nano-synthesis Technology



Research



Top-down versus Bottom-up



Physical Properties1. Refractive index

2. Melting & boiling points

3. Density

4. Surface Area

Chemical properties1. Catalytic properties

2. Solubility

3. Stability

4. Reactivity

Properties



Examples of material creation



Size Dependent

Absorption

Absorption spectra of particles with different sizes: with a decrease in particle size, thewavelength of the absorption maximum shifts to lower wavelength.



Size Dependent Emission



Surface Area

Surface area to volume ratioincreases in nanomaterials

A large particle, when dividedinto many small particles,results in exposure of moresurface, thus increasing thesurface area to volume ratio



Types of nanomaterials

0 D Sphere

1 D Nanorods

2 D Sheets 3 D Crystals, cubes



Carbon The Magic Element

One of the first elements known to mankind Latin word "carbo" meaning "charcoal "

llotropes of Carbon Amorphous carbon, Graphite

and Diamond

Graphite Diamond



What are Carbon Nanomaterials?

Fullerenes, carbon nanotubes, Graphite whiskers,

Cones and Nanocrystalline diamond



Fullerenes Basics

Discovery ± 1985 ± Kroto, Smalley and Curl ±

Nobel Prize in Chemistry in 1996

Fullerenes are large carbon-cage molecules. Byfar the most common one is C

60-- also called a

"buckyball"-- but some other relatively

common ones are C70, C76, and C84 (there areplenty of others too)



History of Fullerenes

Truncated icosahedron was known for more than 500 years

1960s soccer-shaped Corannulene was synthesized

1970 Eiji Osawa proposed that a molecule made up of sp2

hybridized carbons could have the soccer structure

1973 - Russian scientists independently proposed the structure

of C60 and predicted some properties and also of C20 the

smallest fullerene

Corannulene ± Buckybowl ± C20H10



Fulleren pentagon and hexagon



An international collaboration

Harry Kroto (U Sussex),

synthesis of interstellar

molecules

Bob Curl (left) and Richard Smalley

(right) (Rice U, Texas),Cluster chemistry

from a laser-supersonic vaporization

beam

Together, the two groups attempted to simulate the

generation of C-containing molecules in the stars. In

1985, they discovered C60, a new allotrope of carbon.

The compound was very stable and accompanied by

amounts of C70 (m/z 840).



C60, high symmetry,fused pentagon &

hexagons

Smalley¶s paper model,Kroto & Curl add C=C¶s

Single bonds in red,C=C in yellow

Fullerene ± Structure



Curl

Smalley

O¶Brien

Kroto

Heath

Discovery of Fullerenes

Nobel Prize in Chemistry in 1996



Why ³Bucky Ball´ or buckminsterfullerene?

R. Buckminster Fuller

1895-1983

Key thinker, visionary, inventor of the 20th

century, impacting architecture, math, art,

philosophy, religion, physics, literature,

urban development & design, industry &

technology.

Inventor of the

geodesic dome



Buckyball Structure

Fullerenes are polyeders built up by coordinated

carbon atoms with 12 pentagons and (n)

hexagons, where the minimum for n is 20.

Fullerenes fulfil the EULER's theorem, where a

polyeder built up from pentagons and

hexagons has to contain exactly 12 pentagons,

to build a closed structure. Following this rule,the dodekaheder with 20 carbon atoms is the

smallest possible fullerene.

For the stability of the structure, it is important that no pentagons

are side by side. This is described by the Isolated Pentagon Rule(IPR). If two pentagons are adjacent, the tension of the binding is

increasing and the structure is not any more energetically stable.



Discovery of CNT

Discovered by Dr.Sumio Ijima,NEC, Japan in 1991

Discovery accidental during the synthesis of

f ullerenes(C60)

Rapid increase in publications in the last 15years ²More than 15000 publications involvingCNTs in the literature

Generated great interest in several applicationsincluding field emission devices, nanoscaletransistors, tips for scanning microscopy or

components for composite materials



What are carbon nanotubes?

CNT is a new molecular form of carbon andconfigurationally equivalent to twodimensional graphene sheet rolled into a tube

Quite distinct from diamond and graphite

Novel nanostr uctures and the most commonlyused building blocks of nanotechnology

Two Types

Single - wall CNT (SWCNT)

Multi-wall CNT (MWCNT)



SWCNT Single-wall carbon nanotube (SWCNT) ²

consist of a single tube of graphite formed byrolling a sheet of graphene into a cylinder along an (m,n) lattice vector in the grapheneplane.

The (m,n) indices determine the diameter andchirality ² the key parameters of CNT

Depending on the chirality, CNTs can beeither metals or semiconductors



Some SWCNT with different

chiralities

Armchair

Zigzag

Chiral



MWCNT

Multi-wall carbon nanotube (MWCNT) ² consist

of several concentric tubes of graphite fittedone inside the other



Some special properties of CNTs

High surface area

Extraordinary mechanical properties - Tensilestrength is one hundred time more thansteel.Young·s modulus is over 1 Tera Pascal. It

is stiff as diamond. The estimated tensilestrength is 200 Gega Pascal.

Thermal conductivity is higher than diamond

Electrical conductivity similar to copper

Can be metallic or semiconducting



Applications:

Catalysis

It binds to HIV

Antibacterial activity-Destroy the cell wallsof bacterium

Envirmental - odour removal

Surface enchanced Raman spectra

Coloring agents ²ancient days

Drug delivery , unknown action in the body.

To destroy cancer cells

Electronics

optics



Metallic Nanoparticles

Synthesis



Other applications

Solar cells

Sun screen lotions

Paints TiO2

Pt-Ru electrocatalyst for fuel cell



Thank

You All !

sri pushpam nano-new,gcm,ppt

Documents