Transcript Unit 3 Nanomaterials Introduction • Definition – 1-100 nm in at least one dimension • History – – – – Clay particles Medieval stained glass Carbon black Maya blue, ~1000 atoms, blue crystal pigment.

Unit 3 Nanomaterials
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Introduction
• Definition – 1-100 nm
in at least one
dimension
• History
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Clay particles
Medieval stained glass
Carbon black
Maya blue, ~1000
atoms, blue crystal
pigment which can last
for 1000 years.
– Fumed silica
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Types of Nanomaterials
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Micelles
Fullerenes
Quantum dots
Nanocrystals
Dendrimers
Liposomes
Nanowires
Nanotubes
Block copolymer
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Micelle
Hydrophobic
Hydrophilic
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Micelle
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Liposome
Which is hydrophobic and hydrophilic?
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Block Copolymers
A-A-A-A-B-B-B-B
http://www.princeton.edu/~polymer/block.html
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Directed Assembly
of Block
Copolymer Blends
into Nonregular
Device-Oriented
Structures
Mark P. Stoykovich et al
Science June 3, 2005
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Dendrimers
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Quantum Dots
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Surface Area
• Many advantages
of nanomaterials
come from their
large surface
areas.
• The smaller you
make a particle the
greater the surface
area becomes
compared to the
volume.
Sphere
V = πr
2
SA = 4πr
4
3
3
Cube
V=x
3
SA = 6x
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Surface Area
Calculate the surface area 50
nanometer aluminum
particles in m2/g.
Density = 2.7 g/cm3
Sphere
V = πr
2
SA = 4πr
4
3
3
Cube
Calculate the surface area
150 nanometer gold
nanoparticles in m2/g.
V=x
3
SA = 6x
12
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Preparation
Six methods:
• Natural nanoparticles
• Ball milling
• Plasma arcing
• CVD
• Electro-deposition
• Sol Gel
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Natural Nanoparticles
• Many clays are of nanometer size particles.
• These can be added to polymers to form nanocomposites with
unique properties.
• Southern Clay Products http://www.scprod.com/
• They may need to be processed in some way to facilitate
incorporation into a polymer.
• Clays tend to be hydrophillic.
• They can be treated with coupling agents to ensure compatibility
with plastics.
• Organic ammonium cations are used.
• http://www.micchem.com/products/SilaneCouplingAgents.htm
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Clays
http://www.glossary.oilfield.slb.com/Display.cfm?Term=smectite
http://www.soils.wisc.edu/virtual_museum/soil_smectite/
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Ball Milling
• Like an automatic mortar and
pestle.
• From 1 hour to hundreds of hours.
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Plasma arcing
• Used primarily for CNTs
• Co-Cu nanoparticles
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Chemical Vapor Deposition CVD
Reactantsg → Productss
SiH4(g) + N2O(g) → SiO2(s) + NH3(g)
• Low pressure LPCVD
• Plasma enhanced: PECVD, PE-LPCVD
• Temperature, pressure, flow, power
• Well understood system used extensively
in microelectronics
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Silane Reactions
Deposition
SiH4(g) + N2O(g) → SiO2(s) + NH3(g)
Hydrolosis
H3C
O
O
H3C
Si
CH3
O
+ H2O → CH3OH +
O
CH3
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Silica
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Sol Gel
Sols are dispersions of colloidal particles typically
sized 1-100 nm in a liquid.
Gels are interconnected, rigid networks with
pores of sub-micrometer dimensions and
polymeric chains whose average length is greater
than a micron.
The sol-gel process is a name given to the
hydrolysis and poly-condensation of inorganic
compounds to form ceramic materials.
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Sol Gel
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Silica Gels
• Allow us to prepare glass/silica materials at
room temperature.
• Factors effecting sol-gels:
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pH
Time and temperature
Concentration
Catalyst
H2O/Si molar ratio
Aging time and temperature
Drying
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Hydrolosis
Si(OC2H5)4 + H2O → Si(OC2H5)3(OH) + C2H5OH
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Zr Y and Alumino Silicate Gels
• Sol Gels can be
used to form
nanosized particles
of other elements
besides silicon.
• Imogolite nanotubes
can be formed.
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Trapping by Sol-Gels
• Organic or biological molecules can be
trapped in silica using sol-gels because
the are prepared at room temperature.
Ordinarily glass is prepared at 1000°C.
• Can be used to prepare transparent
sunscreens by encapsulating
nanoparticles in smooth, cosmetically
acceptable microparticles of silica.
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2D Nanostructures
GaN, WS2 , MoS2 , NiCl2 , SnS2
Si, CuO, WO
Silica nanoribbons
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