Properties Module

Properties

Module Outcomes• Have an understanding of bulk properties (classical

effects)• Have an awareness of how properties change at

the nanoscale (quantum effects)• Compare the properties of nanoparticles to their

bulk properties• Understand the link between surface area, size of

particles and reactivity• Understand that many materials acquire new and

better properties at the nanoscale and this is leading to an influx of nanotechnology products/ procedures.

What If?… you could do something new with an

old material?

Image: Courtesy K. Alford Bridge8

• Gold?• Magnets?• Wire?• Carbon?• Light source?• Glass?

Gold Gold NanoparticlesDescription

• Clumps of gold molecules forming nano-sized particles

Properties• Different colours depending on size• Semiconductors• More reactive.

Image: Schatz Group, Northwestern University

Different sized nanoparticles

Same material (gold atoms)

Different Optical properties - colours

Gold Nanoparticles

Current• Gold nanoparticles are found in products like paint,

inkjet paper, textiles, and cosmetics

Future• For sensitive diagnostic tests and novel treatments such

as in the detection of Alzheimer's disease• Nanobullets that heat up and kill cancer cells• In computing/electronics/printing data storage, where

gold nanoparticles can be used to increase the speed at which data can be written

• Nanogold conductive inks.

Applications

Magnets FerrofluidsDescription

• Ferrofluids are composed of nanoscale ferromagnetic particles suspended in a carrier fluid, usually an organic solvent or water

Properties• Sticks to magnets• Takes on 3-Dimensional shape

of a magnetic field• Changes density in proportion to magnetic field strength.

Image: S. Kodama & M. Takeno @ Ars Electronica

Different sized nanoparticles

Same material (compound haematite)

New properties (liquid magnet) respond to

environment

Ferrofluids

Current• Damping speakers, graphic

plotters instrument gauges.• Inks and money• Seals- gas lasers, motors,

blowers, hard drives

Future• Biomedical through attaching

drugs to magnetic particles• Proposed artificial heart• Retinal repair in place of eye

surgery.

Applications

Image: S. Kodama & M. Takeno @ Ars Electronica

Wire Shape Memory AlloysDescription

• Shape memory alloys are alloys that have different metallic structures at different temperature

• They can be made to return to a previous shape via phase transformation

Properties• Shape memory alloys have

similar properties to human hair and human tendons

• Can be set to return to an original ‘remembered’ shape.

Image: Courtesy Bridge8/Flinders University

Same material (alloy of Ni and Ti)

Special metallic structure

New properties mean response to a

change in temperature

Shape Memory AlloysApplications

• Orthodontics• Heart surgery• Robotics• Textiles• Creative artwork.

Image: Courtesy Bridge8/Flinders University

Carbon Carbon NanotubesDescription

• A web of carbon atoms formed into a tube shape

• Can be single walled or multi-walled

Properties• Strength• Enhanced conductivity• Very good thermal

conductors, important for electronic nano circuits.

Image: Schwarzm, Wikipedia

Same element (carbon)

Carbon atoms are arranged in a special way

New enhanced properties, now 1000x

stronger than steel

Carbon Nanotubes

Current• Extreme strength allows many

applications:– Reinforcement– Sporting equipment – Electronic nano-circuits

Future• Tear resistant clothing• Flexible computer displays• Space elevator• Combat armor.

Applications

Image: Schwarzm, Wikipedia

Light Source Quantum DotsDescription

• A nano-scale crystalline structure made from cadmium selenide

• Absorbs white light and then reemits it a couple of nanoseconds later in a specific color

Properties• Semiconductors• Quantum dots are so small

that adding or removing an electron can change the properties

• The size of the quantum dot can change the colour emitted.

Image: Dr. D. Talapin, University of Hamburg

Same material (compound)

Different sized nanoparticles

Different optical properties-

different colours

Quantum Dots

Current• Medical markers• Data storage• Quantum dots can be used to

light up cancer cells.

Applications

Image: Gao et al (2004). Nat Biotechnol, 22:969-976, Dr. D. Talapin, University of Hamburg

Glass AerogelDescription

• Aerogels resemble gels, but are composed of mostly air rather than liquid (also called nanofoams or frozen smoke)

Properties• Semi transparent• Low acoustic conductivity• Low density• Brittle.

Image: John Barrie @ flickr

Same material (silica)

Nanostructured

Different properties - insulator

Aerogel

• Excellent insulator (can withstand more than 500oC).

Applications

Image: John Barrie @ flickrWatch video- http://www.youtube.com/watch?v=kHnen2nSmDY

Activity 1 Bulk Properties Of Elements

What do we know about bulk properties of elements?

Image: Nature blog, courtesy Emily Unell

Experiment 1 Teacher Demonstration

Same material–different behaviour!

Image: By Mike Walker on Popsci.com.au

• What happens when you burn a nail in the hot part of a Bunsen flame?• What happens when you burn steel wool with a match or any flame?• Can you explain why the same material behaves differently?

Activity 2 Surface Area Of Cubes

Does the surface area of a cube change if you divide it into smaller cubes?

Image: Booyabazooka, Wikimedia

Properties Change At The Nanoscale

• If the cube is continually cut, the surface area will increase but the volume does not change

• This is significant in nanoscience - nanoparticles acquire new chemical or physical properties

• You will now do three experiments to illustrate how properties change at the nanoscale.

Experiment 2 Surface Area

Properties change at the nanoscale.

How does the surface area affect the rate of change?

Image: Maria Kaloudi @ stock.xchng, Jade Gordon @ stock.xchng

Experiment 3 Making Gold Nanoparticles

Properties change at the nanoscale.

Image: Courtesy Bridge8/Flinders University

Experiment 4 Making Ferrofluid

Properties change at the nanoscale.

Image: S. Kodama & M. Takeno @ Ars Electronica

What Happens To Bulk Properties At The Nanoscale?

• At the nanoscale materials acquire special/new properties

• Two different sized nanoparticles of the same material may have different properties.

What Happens To Bulk Properties At The Nanoscale?

• Smaller particles acquire new chemical or physical properties

• Some properties of nanoparticles are due to surface area

• Small particles have a larger percentage of atoms on the surface

• Small particles have a high surface to volume ratio

• Finer sugar grains have a vastly larger surface area than larger chunks

• The larger the exposed surface, the faster the dissolution (or reaction rate) because the solvent has greater access to the solute.

Discussion of Experiment 2

Image: Mipan @ stock.xchng

What Happens To Bulk Properties At The Nanoscale?

Discussion of Experiment 3Gold acquires new properties at the nanoscale.

Images: © Dorling Kindersly

What Happens To Bulk Properties At The Nanoscale?

Discussion of Experiment 4Nano-sized particles allow for a magnet in liquid phase rather than solid.

Images L to R: Courtesy Bridge8/Flinders University

DefinitionsSo what is nanoscience?Nanoscience is the study of phenomena and manipulation of materials at the atomic, molecular and macromolecular scales where properties differ significantly from those at a larger scale. So what is nanotechnology?Nanotechnology is the design, characterisation, production and application of structures, devices and systems by controlling shape and size at the nanometre scale.

Definition from Royal Society and Royal Academy for Engineering 2004

Revision1. List 5 bulk properties of metals.2. Why are properties of materials at the

nanoscale important in nanotechnology?3. Why does steel wool burn producing a flame,

while a steel nail remains red hot4. Draw up a table and compare the bulk and

nanoscale properties of– Gold– Shape Memory Alloy– Ferrofluids– Carbon Nanotubes.