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Unit 3 Nanomaterials

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Introduction

• Definition – 1-100 nm Definition – 1-100 nm in at least one in at least one dimensiondimension

• HistoryHistory– Clay particlesClay particles– Medieval stained glassMedieval stained glass– Carbon blackCarbon black– Maya blue, ~1000 Maya blue, ~1000

atoms, blue crystal atoms, blue crystal pigment which can last pigment which can last for 1000 years.for 1000 years.

– Fumed silicaFumed silica

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Types of Nanomaterials

• MicellesMicelles• FullerenesFullerenes• Quantum dotsQuantum dots• NanocrystalsNanocrystals• DendrimersDendrimers• LiposomesLiposomes• NanowiresNanowires• NanotubesNanotubes• Block copolymerBlock copolymer

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Micelle

HydrophobicHydrophilic

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Micelle

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Liposome

Which is hydrophobic and hydrophilic?

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Block Copolymers

http://www.princeton.edu/~polymer/block.html

A-A-A-A-B-B-B-B

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Directed Assembly of BlockCopolymer Blends into NonregularDevice-Oriented StructuresMark P. Stoykovich et alScience June 3, 2005

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Dendrimers

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Quantum Dots

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Surface Area

• Many advantages Many advantages of nanomaterials of nanomaterials come from their come from their large surface large surface areas.areas.

• The smaller you The smaller you make a particle the make a particle the greater the surface greater the surface area becomes area becomes compared to the compared to the volume.volume.

343V = πr

2SA = 4πr

3V = x2SA = 6x

Sphere

Cube

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Surface Area34

3V = πr2SA = 4πr

3V = x2SA = 6x

Sphere

Cube

Calculate the surface area 50 nanometer aluminum particles in m2/g.

Density = 2.7 g/cm3

Calculate the surface area 150 nanometer gold nanoparticles in m2/g.

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Preparation

Six methods:Six methods:

• Natural nanoparticlesNatural nanoparticles

• Ball millingBall milling

• Plasma arcingPlasma arcing

• CVDCVD

• Electro-depositionElectro-deposition

• Sol GelSol Gel

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Natural Nanoparticles

• Many clays are of nanometer size particles.Many clays are of nanometer size particles.• These can be added to polymers to form nanocomposites with These can be added to polymers to form nanocomposites with

unique properties.unique properties.• Southern Clay Products Southern Clay Products http://www.scprod.com/http://www.scprod.com/• They may need to be processed in some way to facilitate They may need to be processed in some way to facilitate

incorporation into a polymer.incorporation into a polymer.• Clays tend to be hydrophillic.Clays tend to be hydrophillic.• They can be treated with coupling agents to ensure compatibility They can be treated with coupling agents to ensure compatibility

with plastics.with plastics.• Organic ammonium cations are used.Organic ammonium cations are used.• http://www.micchem.com/products/SilaneCouplingAgents.htmhttp://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 Like an automatic mortar and pestle.pestle.

• From 1 hour to hundreds of hours.From 1 hour to hundreds of hours.

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Plasma arcing

• Used primarily for CNTsUsed primarily for CNTs

• Co-Cu nanoparticlesCo-Cu nanoparticles

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Chemical Vapor Deposition CVD

ReactantsReactantsgg → → ProductsProductsss

SiHSiH4(g)4(g) + N + N22OO(g)(g) → SiO→ SiO2(s)2(s) + NH + NH3(g)3(g)

• Low pressure LPCVDLow pressure LPCVD

• Plasma enhanced: PECVD, PE-LPCVDPlasma enhanced: PECVD, PE-LPCVD

• Temperature, pressure, flow, powerTemperature, pressure, flow, power

• Well understood system used extensively Well understood system used extensively in microelectronicsin microelectronics

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Silane Reactions

Si OO

O

OCH3

CH3

CH3

CH3

+ H2O → → CH3OH +

SiHSiH4(g)4(g) + N + N22OO(g)(g) → SiO → SiO2(s)2(s) + NH + NH3(g)3(g)

Deposition

Hydrolosis

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Silica

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Sol GelSols are dispersions of colloidal particles typically Sols are dispersions of colloidal particles typically sized 1-100 nm in a liquid.sized 1-100 nm in a liquid.

Gels are interconnected, rigid networks with Gels are interconnected, rigid networks with pores of sub-micrometer dimensions and pores of sub-micrometer dimensions and polymeric chains whose average length is greater polymeric chains whose average length is greater than a micron.than a micron.

The sol-gel process is a name given to the The sol-gel process is a name given to the hydrolysis and poly-condensation of inorganic hydrolysis and poly-condensation of inorganic compounds to form ceramic materials.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 Allow us to prepare glass/silica materials at room temperature.room temperature.

• Factors effecting sol-gels:Factors effecting sol-gels:– pHpH– Time and temperatureTime and temperature– ConcentrationConcentration– CatalystCatalyst

– HH22O/Si molar ratioO/Si molar ratio

– Aging time and temperatureAging time and temperature– DryingDrying

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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 Sol Gels can be used to form used to form nanosized particles nanosized particles of other elements of other elements besides silicon.besides silicon.

• Imogolite nanotubes Imogolite nanotubes can be formed.can be formed.

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Trapping by Sol-Gels

• Organic or biological molecules can be Organic or biological molecules can be trapped in silica using sol-gels because trapped in silica using sol-gels because the are prepared at room temperature. the are prepared at room temperature. Ordinarily glass is prepared at 1000Ordinarily glass is prepared at 1000°C.°C.

• Can be used to prepare transparent Can be used to prepare transparent sunscreens by encapsulating sunscreens by encapsulating nanoparticles in smooth, cosmetically nanoparticles in smooth, cosmetically acceptable microparticles of silica.acceptable microparticles of silica.

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2D NanostructuresGaN, WS2 , MoS2 , NiCl2 , SnS2GaN, WS2 , MoS2 , NiCl2 , SnS2Si, CuO, WOSi, CuO, WOSilica nanoribbonsSilica nanoribbons