Introduction to polymer nanocomposite

1. Polymer Nanocomposities
Prof. V. Krishnakumar
Professor and Head
Department of Physics
Periyar University
Salem – 636 011, India

2. Nanocomposites
"Composite Materials" are a new emerging class of
materials to overcome the limitations of monolithic
conventional materials.
Why Nanocomposites
Small filler size:
– High surface to volume ratio
• Small distance between fillers ® bulk interfacial material
– Mechanical Properties
• Increased ductility with no decrease of strength,
• Scratching resistance
– Optical properties
• Light transmission characteristics depends on particle size

3. Polymer Nanocomposites
-Combination of a polymer matrix and inclusions that
have at least one dimension (i.e. length, width, or
thickness) in the nanometer size range known as polymer
nano composities.
• Polymers are light weight
• Corrosion-resistant materials.
• Traditional composites: the length scale of the
fillers is in micrometers.

4. What is a polymer?
• A long molecule
made up from lots of
small molecules
called
• monomers.

5. All the same monomer
• Monomers all same
type (A)
• A + A + A + A 
• -A-A-A-A-
• eg poly(ethene)
polychloroethene
PVC

6. Different monomers
• Monomers of two
different types A + B
• A + B + A + B
 -A-B-A-B-
• eg polyamides
• polyesters

7. Addition polymerisation
• Monomers contain C=C bonds
• Double bond opens to (link) bond to next
monomer molecule
• Chain forms when same basic unit is
repeated over and over.
• Modern polymers also developed based
on alkynes R-C C - R’

8. Copolymerisation
• when more than one monomer is used.
• An irregular chain structure will result eg
propene/ethene/propene/propene/ethene
• Why might polymers designers want to
design a polymer in this way?
• (Hint) Intermolecular bonds!

9. Metallic Nanocomposites
Metals – size dependent property.
Metallic nanoparticles + polymers
Interesting for functional applications
because the properties of nano- sized metals
(optical, magnetic, dielectric, and thermal transport
properties) leave unmodified after embedding in
polymers.

10. Nonlinear optical properties
of nanomaterials
EM wave + nanomaterials
Surface Plasma Resonance effect
Various nonlinear susceptibilities

11. 3rd optical nonlinearity of routine materials
NLO Materials Third order
NLO (m2/W)
Response time
(S)
Large 3rd order and fast response time -Essential
Organic polymers 10-16 – 10-17 10-15
Semiconductors 10-17 10-13
Liquid crystals 10-7 10-6
Normally large 3rd nonlinear susceptibility and ultrafast
response are difficult to achieve simultaneously however this
can be achieved by using organic polymers

12. Versatility of Nano Composites
110
110
120
90
90
100
70
70
80
50
50
60
30
30
40
10
10
20
0
200 300 400 500 600 700 800
Wavelength (nm)
Transmittance (%)
-10
200 300 400 500 600 700 Wavelength (nm)
Transmittance (%)
-10
200 300 400 500 600 700 800
Wavelength (nm)
Transmittance (%)
Host Polymer
possible to tailor the
properties of
composite materials
by selecting, shaping
and distributing the
raw materials
can develop or
design new materials
with desired or
improved properties
Agglomeration
Absorption band
edge falls in invisible
region
Monodispersed
Absorption edge
falls in visible
region

14. Band gaps of different bulk and
nanocrystalline semiconductors
Material Bohr radius
(aB) in Å
Bulk band gap
(Eg ) in eV
Nano form-
Band gap (En,g)
in eV
ZnS*
CdS†
PbS
15
30
200
3.5
2.4
0.4
5.2
5.52
5.2
These differences in properties of nanoparticles are used in
microelectronics, quantum dot lasers, chemical sensors, data storage,
and a host of other applications
*Oleksandr L. Stroyuk, Volodymyr M. Dzhagan, Vitaliy V. Shvalagin, and Stepan Ya.
Kuchmiy J. Phys. Chem. C 114 (2010) 220–225
†K. Manickathai, S. Kasi Viswanathan, M. Alagar, Indian J. Pure. Appl. Phys 46 (2008) 561-
566

15. Properties
Depend on Matrix, NanoFillers, etc
Improved Properties
Mechanical Properties (tensile
strength, stiffness, toughness)
Thermal expansion
Thermal conductivity
Ablation resistance
Chemical resistance
Disadvantage
Viscosity increase (limits
processability)
Sedimentation
Dispersion and distribution
difficulties

16. Application
Depend on Matrix, NanoFillers etc…
• Automobile (gasoline tanks, bumper, interior and
exterior panels, etc…)
• Electronic and Electrical (Printed circuits and
electronic components)
• Food packing (Containers)
• Cosmetics (Controlled release of “active
ingredients)
• Environment (Biodegradable materials)
• Gas barrier (Tennis balls, food and beverage
packing)
• Military and aerospace