1 Unit 3 Nanomaterials

2 Introduction Definition – nm in at least one dimensionDefinition – nm in at least one dimension HistoryHistory –Clay particles –Medieval stained glass –Carbon black –Maya blue, ~1000 atoms, blue crystal pigment which can last for 1000 years. –Fumed silica

3 Types of Nanomaterials MicellesMicelles FullerenesFullerenes Quantum dotsQuantum dots NanocrystalsNanocrystals DendrimersDendrimers LiposomesLiposomes NanowiresNanowires NanotubesNanotubes Block copolymerBlock copolymer

4 Micelle Hydrophobic Hydrophilic

5 Micelle

6 Liposome Which is hydrophobic and hydrophilic?

7 Block Copolymers A-A-A-A-B-B-B-B

8 Directed Assembly of Block Copolymer Blends into Nonregular Device-Oriented Structures Mark P. Stoykovich et al Science June 3, 2005

9 Dendrimers

10 Quantum Dots

11 Surface Area Many advantages of nanomaterials come from their large surface areas.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.The smaller you make a particle the greater the surface area becomes compared to the volume. Sphere Cube

12 Surface Area Sphere Cube Calculate the surface area 50 nanometer aluminum particles in m 2 /g. Density = 2.7 g/cm 3 Calculate the surface area 150 nanometer gold nanoparticles in m 2 /g.

13 Preparation Six methods: Natural nanoparticlesNatural nanoparticles Ball millingBall milling Plasma arcingPlasma arcing CVDCVD Electro-depositionElectro-deposition Sol GelSol Gel

14 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 unique properties.These can be added to polymers to form nanocomposites with unique properties. Southern Clay Products Clay Products They may need to be processed in some way to facilitate incorporation into a polymer.They may need to be processed in some way to facilitate incorporation into a polymer. Clays tend to be hydrophillic.Clays tend to be hydrophillic. They can be treated with coupling agents to ensure compatibility with plastics.They can be treated with coupling agents to ensure compatibility with plastics. Organic ammonium cations are used.Organic ammonium cations are used.

15 Clays

16 Ball Milling Like an automatic mortar and pestle.Like an automatic mortar and pestle. From 1 hour to hundreds of hours.From 1 hour to hundreds of hours.

17 Plasma arcing Used primarily for CNTsUsed primarily for CNTs Co-Cu nanoparticlesCo-Cu nanoparticles

18 Chemical Vapor Deposition CVD Reactants g → Products s SiH 4(g) + N 2 O (g) → SiO 2(s) + NH 3(g) SiH 4(g) + N 2 O (g) → SiO 2(s) + NH 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 in microelectronicsWell understood system used extensively in microelectronics

19 Silane Reactions → + H 2 O → CH 3 OH + SiH 4(g) + N 2 O (g) → SiO 2(s) + NH 3(g) Deposition Hydrolosis

20 Silica

21 Sol Gel Sols are dispersions of colloidal particles typically sized 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.

22 Sol Gel

23 Silica Gels Allow us to prepare glass/silica materials at room temperature.Allow us to prepare glass/silica materials at room temperature. Factors effecting sol-gels:Factors effecting sol-gels: –pH –Time and temperature –Concentration –Catalyst –H 2 O/Si molar ratio –Aging time and temperature –Drying

24 Hydrolosis Si(OC 2 H 5 ) 4 + H 2 O → Si(OC 2 H 5 ) 3 (OH) + C 2 H 5 OH

25 Zr Y and Alumino Silicate Gels Sol Gels can be used to form nanosized particles of other elements besides silicon.Sol Gels can be used to form nanosized particles of other elements besides silicon. Imogolite nanotubes can be formed.Imogolite nanotubes can be formed.

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

27 2D Nanostructures GaN, WS2, MoS2, NiCl2, SnS2 Si, CuO, WO Silica nanoribbons