Smart materials and nanoparticals

Smart materials are materials that behave differently depending on the conditions they are under.

 Nitinol, this is a shape memory alloy (it is half nickel, half titanium).

• It is heated up to above a certain temprature and bent into any position.
• once it has cooled down it becomes very bendy again.
• as soon as it heats up again it will retern to the position it was in when it was first heated.
• (when bent too far when cool it will stay bent though).

This is what is used for braces as the heat of your mouth makes the wire want to retern to a straight position, but because it is attatched to your teeth it pulls them straight too.

It's also used for the frames of glasses, this means when you bend your glasses you can just put them in hot water and they will straighten out again.

These are really really really tiny particles, 1-100 nm across, They contain roughly a few hundred atoms.

 (really say how tiny they are in the exam, you will not get the mark if you just put small)

One type of nanoparticles are fullerenes:

• Fullerenes are molecules of carbon shaped in hollow balls or tubes.
• These hollow balls and tubes are made up of many hexagonal rings of carbon atoms.
• Fullerenes can be joined together to make nanotubes.
• These are very strong and can be used to reinforce materials such as graphite

Due to the high surface area to volume ratio, they are good for catalysing reactions.

They can be used to make highly specific sensors that only detect one type of molecule (used to test water purity) .

Sun tan cream because the particles are so small they don't leave marks on the skin.

Nanomedicine because it is absorbed easily into the body due to being so small.

The ball shaped nanoparticles are good lubricants for artifical joints and gears as they work like miniature ball bearings.

Nanotubes can be used to make microscopic wires in electrical circuits in computer chips because they conduct electricity.