DESIGNING NANOMATERIALS: NOVEL

APPROACHES

SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH19, UNIVERSITY ROAD, DELHI-110 007

Email : sridlhi@vsnl.com Website : www.shriraminstitute.org

Presented by :Dr. R.K. KHANDAL

OUTLINE

Scope

Opportunities

Challenges

Nanomaterials

SRI & Novel Nanomaterials

Classification

Size Effects

Shape Effects

Approaches

Novel Architecture

Nanomaterials:

Materials consisting of particles of the size of nanometer

Volume = Surface Area * Thickness

For a given volume:

Surface area Thickness

More atoms at surface than in the interior

Extraordinary activity

SCOPE: DEFINITION

SCOPE : DOMAIN

Keywords Domain

Particle size Distribution in the continuous phase

Modification of surfaces Interfacial tension

Surfaces Interfaces

Rising volume fraction Homogeneity of phases

of dispersing phase Domain of Nanotechnology: Multi-phase systems

Liquid : Liquid Solid : Liquid

Surfaces and interfaces involving different phases

Gas : Liquid

Gas : Solid

Systems Process

Emulsion Macro Micro

Dispersion Coarse Fine

Solution Colloid

SCOPE: PROCESS

A process to create a continuous dispersed phase as fine as possible for homogeneity with the dispersing phase

(Liquid / Liquid; Gas/Liquid)

(Solid / Liquid)

(Solid / Liquid; Liquid/Liquid)Solubilization

SCOPE : DIMENSIONS

What Happens Dimensions

Particle size More from less

Surface area Enhanced coverage

Activity Novel products

Efficiency Improved performance

per unit mass Maximum possible benefits from minimum possible inputs

Effecting changes through and at atomic scale

NANOSCIENCE TO NANOTECHNOLOGY“MACRO TO NANO”

MATERIALS

Copper

Macro

PROPERTIES

Nano

Opaque Transparent

Platinum Catalyst

Aluminium Stable Combustible

Inert

Gold Inert Catalyst

Unique properties at the nanoscale are the driving force for exploitation of nanomaterials

NANOSCIENCE TO NANOTECHNOLOGY

NANOSCIENCE NANOTECHNOLOGYBiology

Chemistry

Physics

Value Addition

Performance

Diversification

Measure of success of science and technology is to manufacture and commercialize!

OPPORTUNITIES: NANOTECHNOLOGY

N

A

N

O

S

C

I

E

N

C

E

Carbon

Nanotube

Nanowire

NANOTECHNOLOGY

Carbon nanotube on plastics

Array of Carbon nanotube-devices

TiO2

Sunscreens

CoatingsNano-TiO2

OPPORTUNITIES: NANOMATERIALS FOR INDUSTRIES

NANOMATERIALS

Electronics

Chemicals Energy

Transportation

Medical/Biology Materials

Water

PurificationDesalination

Agriculture

FertilizersPackagingCoatings

Light weightEfficiency

ProsthesisDrug deliveryDiagnosis

CompositesCoatingsConstruction

Data storage High speed devices

Catalysts Fuel CellsBatteries

Nanotechnology has revolutionized various industries; only solution for the emerging needs

Process of making Nanomaterials

Process steps Inputs

Macro

Micro

Nano

CHALLENGES: PROCESS TECHNOLOGY

Challenge: To have a process that can convert macro materials into nano materials spontaneously & with minimum efforts

Energy

Bulk

Sugar cube

Nano

Dissolved sugar/salt

Bulk

Output

Salt

NANOMATERIALS:CLASSIFICATION

Nanoparticles

(Smoke, diesel, fumes)Nanocrystalline

Materials Nanoparticle composites

Nanocrystalline films

Nanorods tubes (Carbon nano tubes) Inter connects

Multi layer structure Nano Films Foils

Nantube, reinforced composites

Surface layers

Class 1Discrete

Class 2Surface

Class 3Bulk0-D

d 100 nm

1-D

d 100 nm

2-D

d 100 nmDim

ensi

onal

ity

Multi layer structure Nanowires & Nanotubes Multi layers

3-D

3-D nanomaterials are nanocomposites formed of two or more materials with very distinctive properties, act synergistically to create unique properties that cannot be achieved by single materials

NANOMATERIALS: SIZE DEPENDENCE

Particle size (nm)

Me

ltin

g p

oin

t (K

)

Particle size (nm)

Su

rfa

ce T

ens

ion

(m

N/m

)

Particle size(µm)(nm)

Str

en

gth

Die

lec

tric

C

on

sta

nt

Particle size (nm)100 1000

Bulk

Particle size affects the properties & thus overall behavior of the material

Au Au

AlPbTiO3

NANOMATERIALS : SHAPE DEPENDENT

Sphere

Cylinder Cube

Dimension (nm)

Su

rfa

ce/V

olu

me

(nm

-1)

Nanoscale materials have extremely high surface to volume ratios as compared to larger scale materials

Sphere: S:V = 3 : rCube : S:V = 6 : lCylinder: S:V = 2 : r

r = radiusl = length

DESIGNING OF NANOMATERIALS: APPROACHES

Assembled from nano building blocks

From bulk

Control of size is dependent on end-use applications

DESIGNING OF NANOMATERIALS :SPHERES AND RODS

Ag(I) or Au(III) salt + NaBH4

More Seeds

+ metal salt + ascorbic acid + CTAB

Less Seeds

+ metal salt + ascorbic acid + CTAB

Seed mediated growth is a good approach for the preparation of nanorods and nanowires of varying aspect ratios.

Few seeds Longer rods

Seeds

(Stabilizing agent)

(Stabilizing agent)

[H]

Designing of Nanomaterials: DendrimersLinear Branched Cross-linked Dendritic

Flexible coil

Rigid rod

Cyclic (closed linear)

Polyrotaxane

Random short branches

Random long branches

Regular comb branches

Regular star branches

Lightly cross linked

Densely cross linked

Interpenetrating networks

Hyper branched

Ideal dendron

Dendrimer

X

New types of nanomaterials (nanocomposites) with unusual architecture are created by highly branched polymers.

Dendrimers have characteristic features of both macromolecules and the nanoparticles: Dendrimers help in controlling the particle size.

DESIGNING OF NANOMATERIALS: ENCAPSULATION

TiO2 TiO2

-

-

-

-

-

-

TiO2

TiO2

-

-

-

-

-

-

MonomerPolymer

Surfactant

-

-Radical

Polymerization

Latex Fe2O3-Particles

Fe2O3-ParticlesLatex bead

Pre-treatment

Polymerization

Copolymer layer

Encapsulated particle

Amphiphilic molecule

Monomer

Polymer encapsulated nanomaterials are used for targeted delivery of substances such as drugs.

Dimensions of encapsulated substance is tens of nanometers and of the stabilizing shell is a few hundred micrometers.

Designing of Nanomaterials: Optical

Incident Light

Transmitted light (Spectral luminous gain, switching, fluorescence, etc.

Optically functional particles

Coating or fibers of the matrix formed

Metal ions can be introduced into polymeric fibers to produce colored light guides.

Polymer based nanocomposites containing well-dispersed inorganic particles can exhibit semiconducting properties, quantum dot effects, non-linear optical properties and extremely low or high refractive index.

DESIGNING OF NANOMATERIALS : MAGNETIC MATERIALS

Isolated nanoparticles

Nano particles

Ultrafine Nanoparticles core shell morphology in the matrix

Small magnetic nanoparticles embedded in a chemically dissimilar matrix

Small particles dispersed in nanocrystalline matrix Magnetic property corer with

polymer coating

The characteristics of magnetic matrices depend on diversity of interconnected factors

< 1 nm:Non-magnetic ~ 1-10 nm:Super paramagnetic >10 nm: Ferromagnetic

Ex. Mn,Co,Fe &Ni

3M2O3.5Fe2O3

Ni0.5Zn0.4Cu0.1Fe2O3

DESIGNING OF NANOMATERIALS: ELECTRICAL MATERIALS

Matrix

Conductivity of nanoparticles is higher than for micron size particles Nanoparticles-polymer interactions influences electro-physical properties Size & form of nanoparticles Magnetic characteristics

Conductivity can exist in every single metal nanoparticle

Structures of composites

Statistical

Layered Chain

Globular

Examples: Ag,Ni,Cu,Zn

SRI’S EXPERIENCE

SRI has developed nanomaterials for :

Optical applications

Effluent treatment

23232323232323

LOW REFRACTIVE INDEX MATERIALS

The refractive index of low refractive index materials increases from 1.49 to 1.66.

1 . 4 1

1 . 4 7

1 . 5 3

1 . 5 9

1 . 6 5

1 . 7 1

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0

% o f a d d i t i v e

Ref

ract

ive

ind

ex

24242424

Refractive index increases with increase in percentage of metal salt.

1.41

1.42

1.43

1.44

1.45

1.46

1.47

1.48

0 5 10 15 20 25 30Metal salt (% by wt)

Ref

ract

ive

Ind

ex

Barium Hydroxide Lead Monoxide Lanthanum Oxide

EFFECT OF DISPERSION OF METAL SALTS ON THE REFRACTIVE INDEX OF ACRYLIC ACID

252525252525

Effect of metal on refractive index

In-situ formation of nanoparticles of TiThe refractive index of the polymer increases from 1.45 to

1.53

1.44

1.46

1.48

1.5

1.52

1.54

0 2 4 6

% Ti

Re

fra

cti

ve

Ind

ex

MATERIALS FOR ENERGY CONVERSION: SEMICONDUCTORS

Challenge is maneuver the band gap:make it sensitive to visible light.

6.3 eV 3.15 eV 1.58 eV

U.V

200 nm 400 nm 800 nm

Visible

TiO2

ZnOCdS

WO3

Band gap Energy

EMS()

TiO2 = 3.20 eV

ZnO = 3.35 eV

WO3 = 2.80 eV

CdS = 2.42 eV

Semiconductors are the most ideal and preferred materials.

XRD : DOPED TiO2

XRD analysis confirms the doping of TiO2

Change in lattice parameter ‘a’ & ‘c’ of TiO2, confirms the

incorporation of Cd2+ in Ti4+

Influence TiO2 Doped TiO2 Doped TiO2 factor (In-situ) (External)

a/nm 3.0301 3.3184 3.3558 c/nm 9.5726 10.0136 11.2138

Inte

nsi

ty(a

.u.)

Position (2 Theta)20 30 40 50 60 70 80

External

In-Situ method

TiO2 market procured

TiO2 (Reference)

PARTICLE SIZE ANALYSIS : DOPED TIO2

A particle size of 80 - 87 nm of the doped mixture has been

achieved by In-situ methods

Doped In-Situ Doped External TiO2

THANK YOU