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DR. R.K. KHANDAL
DIRECTOR
NANOCOMPOSITES FOR OPTICAL PLASTIC MATERIALS
SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH19, UNIVERSITY ROAD, DELHI - 110007
OUTLINE OF PRESENTATION
OPTICAL APPLICATIONS
OPTICAL PLASTICS
NANO COMPOSITES
METAL CONTAINING PLASTICS
FUTURE OF NANO TECHNOLOGY
An overview presenting, past, present and future options in novel materials
OPTICAL APPLICATIONS
BIOMEDICALS ENGINEERING INSTRUMENTATION INFRA STRUCTURE
OPHTHALMICLENSES
AUTOMOTIVE
AVIATION
SPACE
RADIATION SHIELDING
TELESCOPE
BINOCCULAR
CAMERA
SENSORS
OPTICS
COMMUNICATION(Fibre Optics)
SIGNALS(Railways, Aviation, Road, transport etc.)
SHIELDING
Glass is the most conventional material used in all the above applications; Plastics are viable alternatives
SPECTCLE
CONTACT
INTRAOCULAR
BIO-MEDICAL APPLICATIONS
Optical Devices Parameters Materials Used
Spectacle lenses Refractive index, optical Glass, Polythiourethanesclarity, Abbe number, Polyacrylates, Polycarbonates
Sun glasses Refractive index, UV- Glass, Polyacrylatesresistance, aesthetics
Contact lenses Refractive index, clarity, Polyacrylates and modifiedbiocompatibility, softness/ acrylates, silicones andrigidity modified silicones
Intraocular lenses Refractive index, Polyacrylates and modifiedtransparency acrylates and siliconesbiocompatibility,
Glass has been completely replaced by plastics
Development of newer plastics is the key
INSTRUMENTAL APPLICATIONS
Optical Device Parameters Materials Used
Binocular lenses Magnifying power, Glass, Polyacrylates,Refractive index, clarity Polycarbonates
Telescopes lenses Magnifying power, Glass, Polyacrylates,Refractive index, clarity Polycarbonates
Magnifying glass Magnifying power, Glass, Polyacrylates,Refractive index, clarity Polycarbonates
Tailoring of available materials for achieving varying refractive index Plastics
Plastics provide flexibility and options
INFRASTRUCUTRE APPLICATIONS
Optical Device Parameters Materials Used
Optical waveguides Refractive index, Lithium niobate (LiNbO3), absorbance / Potassium titanyl transmittance phosphate (KTiOPO4)
in polyacrylate
Optical fibres Refractive index, Glass, Polyacrylatesrate of light Metalstransmission
Research is going on for alternate plastic materials for the above applications
Conventional materials would not have been adequate to meets the demand
ENGINEERING APPLICATIONSOptical Device Parameters Materials Used
Optical modulators Refractive index, Lithium niobate (LiNbO3), total internal reflection, Potassium titanyl phosphateinfrared absorbance (KTiOPO4)
Optical demodulators Refractive index, Lithium niobate (LiNbO3), total internal reflection, Potassium titanyl phosphateinfrared absorbance (KTiOPO4)
Optical interconnectors Refractive index, Lithium niobate (LiNbO3), total internal reflection, Potassium titanyl phosphateinfrared absorbance (KTiOPO4)
Liquid crystal dislays Refractive index, Glass, Polyacrylates(LCD) absorbance / transmittance
Use of plastic materials leads to the development of effective, less cumbersome technology
GLOBAL STATUS : PLASTIC LENSES
CHARACTERISTICS
800-850 million lenses per year
7-8 billion in sales
Lens replacement frequency : 2-3 years
Indian requirement is met by imports only
10%
17%
33%
45%
55%
98%
0%
20%
40%
60%
80%
100%
120%
Latin America United States Canada Western Europe Asia Pacific Japan
Countries
% a
s s
ha
re o
f to
tal
len
se
sMARKET FOR ANTI-REFLECTING LENSES
Lens market breakdown by material
Plastic lenses, medium, high
indexes (>1.5 index)
22%
Plastic lenses <1.5 index
42%
Glass lenses36%
MATERIALS USED : LENSES
Clear picture of the gaining popularity for optical plastics
Major plastics is polycarbonate
INDIAN STATUS : LENSES
140 million pieces per year
Export = 112 million pieces per year
Domestic = 28 million pieces per year
Complete requirement is met by imports
Indigenous technologies are required for increase in Indian market demand
Optical plastic industry is engaged in job work
DESIGN CRITERIA FOR OPTICAL PLASTICS
Evaluation of the environment in which the plastic is to be used
Physical and optical properties of the plastics
Physical properties to be considered are density, hardness, rigidity
Service temperature, thermal expansion, electrical and thermal conductivity
CLASSIFICATION OF OPTICAL MATERIALS
Gradient index materials : Glass & Polyacrylates
Low Refractive Index : < 1.5 (CR 39, PMMA & Crown glass)
Medium Refractive Index : 1.5-1.6 (Polycarbonates)
High Refractive Index : > 1.6 (Polythiourethane)
Infrared refractive materials : Fused silica and polycarbonates
Ultra-violet refractive index : Fused silica, polycarbonatesmaterials and Glass
Materials used are fused silica, polycarbonates and glass
OPTICAL PLASTICSPAST
Material : Polymethyl methacrylate (PMMA)
Applications : Spectacle lenses, Contact lenses, Camera lenses, Binocular lenses
Features : High rigidity leading to eye-discomfort in internal wear such as contact lenses. Poor aesthetics leading to bulge eye look.
Poor shatter resistance leading to delicate handling
Availability of the right type of materials was a constraint
PRESENT
Material : Modified acrylates and silicones, Thiourethanes, polycarbonatyes
Applications : Flexible intraocular lenses, Extended wear contact lenses Contact lenses of variable wear
Features : Fixed optical properties Easy to use Economic Better customer appeal
OPTICAL PLASTICS
With newer materials, novel applications have become possible
FUTURE
Material : Organic/ Inorganic hybrid materials, Polymer composites
Applications : Lenses, Optical waveguides,
Optical fillers, Optical transmitters
Features : Wide range of refractive index,Improved stability and hardness,Tailor-making of optical properties possible
OPTICAL PLASTICS
Nano composites have a great potential for future
Advantages Disadvantages
Light weight Soft surfaceImpact resistance Limitation of refractive index
Good machineability Ultra high & low refractive index not possible
Good aesthetics
Good processability
All the above disadvantages can be overcome by only nanocomposites
OPTICAL PLASTICS
Nanocomposites can be designed
NANO MATERIALS : CROSS-SECTIONAL AND INTERDISCIPLINARY APPROACH
AutomotiveComponents
Paper
Cosmetics
Textiles
Displays
Coatings
Emulsions
Dispersions
Plastics
Films
Powders
Science
Chemistry
Physics
Analytics
MaterialScience
Biology
Applications End Products
Materials/Intermediates
Nano-materials
Developing Nanomaterials is a challenge !
TYPES OF NANO-COMPOSITES FOR OPTICAL APPLICATIONS
METAL-GLASS COMPOSITES
METAL-POLYMER COMPOSITES
Areas of application include sensors, wave guides, optical fibres, etc.
Complementary and synergistic compositions for extraordinary effect
TYPES OF NANOCOMPOSITES FOR OPTICAL APPLICATIONS
METAL-GLASS COMPOSITES
Incorporation of metal nanoparticles (Ag, Au) in glass leading to colored glass
Good absorption of incident light: negligible scattering
Concept used since 15th century
Colloidal dispersions of metals in inorganics was an established way
METAL-POLYMER COMPOSITES
Transparency is achieved
Substantial reduction in intensity loss which is size dependent
Refractive index above 2.5 (ultra-high) and refractive index below 1.25 (ultra-low) is possible only with nanocomposites
TYPES OF NANOCOMPOSITES FOR OPTICAL APPLICATIONS
A novel idea of imparting advantageous features of metals to plastics for better
METAL CONTAINING GLASS
Chronology Materials
Potable gold, Potable silver
Prepn. of colored glass by theincorporation of purple, violet, brown or black colloidal powders
Use of colloidal gold powders for the painting of enamel
Detailed analysis of color of gold colloids
Formation of ruby glass using gold particles
Coloured glass with unique features
15th Century
16th Century
17th Century
18th Century
19th Century
20th Century
PRESENT
Materials : Preparation of dichroic films of gelatin and Os, Rh, Ag, Au, P, Hg, As, S, etc. Dichroic films of PVA-Au, Ag & HgSilver add crystallites in ramie, hemp, bamboo, silk, wool, viscose, (5-14nm)
Applications : Eye-wear lenses, cameras, binoculars, sensors, solar applications, filters, transmitters, wave guides, reflectors, etc.
METAL CONTAINING POLYMERS
Metal containing polymers are a novel idea !
FUTURE OF METAL-CONTAINING POLYMERS
NANOPARTICLE
Electronics
Multiuse
Chemical Industries
Defence
OpticsConsumers
Medical/Biology
Solar Cells Sensors
Electrocatalysis
Photocatalysis
For any application, nanotechnology is a blend of the science of physics, chemistry and biology
Field of optics has seen a lot success with nanotechnology; coatings and
diagnostics
As the scale goes down, the activity rises mainly due to the lowering distances at which theinterparticle interactions occur leading to evolution of energy.
Emulsion
High surface energy, Non-homogeneous, unstable
Thermodynamically
ExtremelyHigh
Irreversible
System Scale Activity RemarksMixtures >micrometer Low
Suspension
Dispersion
micrometer Medium kinetically stable
unstableMicroemulsionSolubilised
nanometer ModeratelyHigh stability probable
Thermodynamic
Macromolecular angstrom High
MolecularAtomic
Very High
Nuclear
Spontaneous
atomic
sub-atomic
Thermodynamically stable
Basis for new materialsSource of energy
SIZE - DEPENDENT PROPERTIES OF MATERIALS
CHANGE OF PROPERTIES AT THE NANOMETER SCALE
Chemical reactivity
Electronic properties
Optical properties (absorption, scattering)
Mechanical properties (hardness)
Transport properties (heat, current)
Bioavailability
In addition to quantum effects, the increased surface-volume ratio at the nanometer scale bring improvements in ;
Nanomaterials have extraordinary features
INCREASE IN SURFACE AREA(at constant volume fraction)
1 m 100 nm 10 nm
No. of particles 1 103 106
Surface AreaPer unit volume
1X 10X 100X
Decreasing Particle Size
Combination of two or more phases where at least one phase is in nanometer range
TYPICAL MORPHOLOGIES
FEATURES OF NANOCOMPOSITES FOR OPTICAL APPLICATIONS
Particle size less than 50-100nm leads to less scattering of
light and therefore improves transparency
By incorporation of inorganic colloids with extreme
refractive index in organic polymers ultra high refractive
is possible
High surface to volume ratio improves reduces scattering
losses
Drawbacks of plastics can be eliminated
Tailor-making of refractive index possible
WORK CARRIED OUT AT SRI Selection of suitable metal salts for dispersion
Ba(OH)2, BaSO4, Ba(NO3)2, BaCl2, PbO, (CH3COO)2Pb, PbNO3, LaCl3, La2O3, La(NO3)3, TiO2
Nb2O3, NbC
Acrylic acid as monomer
Selection of polymerization technique Thermal, Gamma Selection of suitable initiator for thermal polymerization Benzoyl peroxide, Azo bis-isobutyronitile (AIBN)
Selection of suitable dose for polymerization by Gamma radiation
Casting of lenses Eight patents on the product & process
Characterization of cast lenses for various opto-mechanical properties Colour Refractive index Abbe number Shore-D hardness Scratch resistance Haze Pencil hardness Impact resistance Machinability Heat distortion (°C) Specific gravity Transmittance (%) Yellowness index LAB value
1.391.4
1.411.421.431.441.451.461.471.48
0 3 6 9 12 15 18 21 24
% age of metal salt
Ref
ract
ive
ind
ex
M-1 M-2 M-3
EFFECT OF METAL SALTS ON REFRACTIVE INDEX OF ACRYLIC PLASTICS
Metal salts are effective in improving the refractive index of acrylic plastics
EFFECT OF CO-MONOMER 1 ON REFRACTIVE INDEX OF METAL DISPERSED ACRYLIC PLASTICS
1.4
1.42
1.44
1.46
1.48
1.5
1.52
0 2 4 6 8 10 12 14
% age of comonomer-1
Re
fra
cti
ve
ind
ex
Significant increase in refractive index of acrylic plastic is obtained with co-monomer 1
M-1 M-2
M-3
1.381.4
1.421.441.46
1.481.5
1.521.541.56
0 2 4 6 8 10 15 20 25 30 35 40 45 50
%age of comonomer-2
Refr
acti
ve in
dex
EFFECT OF CO-MONOMER 2 ON REFRACTIVE INDEX OF METAL DISPERSED ACRYLIC PLASTIC
M-1 M-2
M-3
Significant increase in refractive index of acrylic plastic is obtained with co-monomer 2
PROPERTIES OF GAMMA RADIATIATED SAMPLES CO-MONOMER 1
Dispersion of metal salts resulted in improved optical and mechanical properties of polyacylates
1.1581.2181.044Yellowness index14.
858287Spectral Transmittance (%)12.
1.281.301.31Specific gravity11.
120120120.0Heat distortion (0C)10.
GoodGoodGoodMachinability9.
PassPass PassImpact resistance 8.
4H3H3HPencil hardness7.
6.80-7.0710.7-10.88.24-8.29Haze6.
Grade-BGrade-BGrade-BScratch resistance5.
78-8070-7570-72Shore-D hardness4.
343435Abbe No.3.
1.581.591.56Refractive index2.
Light YellowDark YellowLight YellowColour1.
M-1 M-2 M-3
Metal dispersed polyacrylateAnalysisS. No.
13. Integrated transmittance 0.5563 0.5575 0.5679
0.1592
90
1.23
>120.0
Good
Pass
3H
---
Grade-B
88-90
38-39
1.5603
0.13920.1263Yellowness index14.
8987Spectral Transmittance (%)12.
1.291.24Specific gravity11.
130>120.0Heat distortion (0C)10.
GoodGoodMachinability9.
PassPassImpact resistance 8.
3H3HPencil hardness7.
---2.75-2.84Haze6.
Grade-BGrade-BScratch resistance5.
80-8285-88Shore-D hardness4.
30-3134Abbe No.3.
1.5741.570Refractive index2.
colourlesscolourlessLight yellowColour1.
M-1 M-2 M-3
Metal dispersed polyacrylateAnalysisS. No.
13. Integral Transmittance 0.5933 0.5822 0.7795
PROPERTIES OF GAMMA RADIATIATED SAMPLES CO-MONOMER 2
STANDARD MATERIAL Vs METAL CONTAINING SAMPLES
>2.02.03.0<1.01-2< 1.0Haze,%7.
9092> 908990-9290-95Transmittance6.
1.20-1.301.241.331.201.322.0-5.0Specific gravity5.
GoodPoorModerateModerateGoodPoorImpact resistance
4.
>85< 65>757588-89>90 Shore-D Hardness
3.
35-385726355850-55Abbe number2.
1.56-1.591.451.661.581.491.80Refractive index1.
PA(SRI)
PAPTU(SRI)
PCCR-39GlassPropertiesS.No
Modified polyacrylates can be a good replacement to the conventional optical materials
STANDARD MATERIAL Vs METAL CONTAINING SAMPLES
0.12-1.20.022750.170.07860.00740.0087Yellowness index
13.
0.5533-0.61520.58450.58580.59060.57911.1548Integrated Transmittance
12.
GoodGoodGoodGoodGoodGoodMachinability11.
3H-4H3H6H3H4H6HPencil hardness
10.
Grade-BGrade-DGrade-BGrade-BGrade-BGrade-AScratch resistance
9.
L=51.38-77.05a=-6.25-7.50
b = 23.7-25.50
L=67.50a=6.30
b=20.30
L=67.90,a = 5.50,b = 23.2
L=67.68,a = 6.15,b = 21.8
L=67.44,a = 6.35,b=20.32
L=67.46,a = 6.35,b=20.48
LAB value8.
PA(SRI)
PAPTU(SRI)
PCCR-39GlassPropertiesS.No
Modified polyacrylates can be a good replacement to the conventional optical materials
CONCLUSIONSMaterials can be designed for desired characteristics
Lenses have been cast successfully with barium ,lead and lanthanum salts.
Tailor making of refractive index of polyacrylates have been achieved between 1.550-1.575 using barium salts; 1.560-1.595 using lead salts; 1.550-1.565 using lanthanum salts.
SRI team has been successful in developing metal dispersed nano-composites of polyacrylate with improved Abbe no., hardness, & scratch resistance.
FUTURE OF NANOTECHNOLOGY
Structuresizes
2040 year1960 1980 2020Based on Bachmann, VDI
0.1 nm
0.1 µm
0.1 mm
Nano
Micro
Macro
Integrateduse of
biological principles,physical laws
and chemical know-howComplex chemistry
Electrical engin.
Electronics
Micro-electronics
Material design
Supramolecularchemistry
Quantum effectsCell biology
Molecularbiology Functional
molecule design
Applicationsof
nano-technology
bottom up bottom up
top down
top down
Chemistry
Coatings,cleaning agents,
composite materials,textiles,
cosmetics,displays
Physics
Biology
THANK YOU