New materials Flashcards
Why do smart materials behave differently?
The change depending on the conditions
What is nitinol?
What can you do with it when it is cool?
If you then reheat it above a certain temperature what happens?
A shape memory alloy
Bend it and twist it like rubber, but if too far it stays bent
It goes back to a remembered shape.
Why are smart materials useful for glasses frames?
If you bend them you can put them in warm water and they’ll move back into shape
What is nitinol used for?
Why?
Dental braces
In the mouth it warms up and tries to return to the remembered shape so it gently pulls the teeth with it
How big are nanoparticles?
1nm = how many meters?
1 to 100 nanometers across
0.000,000,001 m (9 ‘0’s in total)
How many atoms do nanoparticles contain?
A few hundred
What is one example of a nanoparticle?
What are these and what are their shapes?
How are the atoms that make them arranged?
fullerenes
Molecules of carbon shaped like hollow balls or closed tubes
The carbon atoms are arranged in hexagonal rings
Different fullerenes contain different ….
numbers of carbon atoms
What is the difference between the nanoparticle and the bulk chemical of that substance?
they have very different properties
What can fullerenes do that makes them so useful?
They can be….
…. makes them very … sot hey are good for …
They can be joined together to form nanotubes, tiny hollow carbon tubes a few nano meters across
All of the covalent bonds make the nanotubes very strong so they can be used to reinforce graphite in tennis rackets
What is nanoscience?
The use and development on nanoparticles
Why are nanoparticles useful in industry?
They have a huge surface area to volume ration so are good for making new industrial cataysts
How are nanoparticles used in relation to water?
They can be used to make sensors to detect one type of molecule and nothing else. They make highly specific sensors that are now used to test water purity.
How are nanoparticles used in relation to construction?
They are used to make stronger and lighter building materials
How are nanoparticles used in relation to cosmetics?
Sun cream and deodorant have been made using these. The small particles do their job but don’t leave white marks on the skin
How are nanoparticles used in relation to medicine?
Nanomedicine is based on the idea that tiny fullerenes are absorbed more easily into the body than most particles, this means they could deliver drugs right into the cells where they’re needed.
How are nanoparticles used in relation to coatings?
New lubricant coatings are being developed using fullerenes as they reduce friction in places like artificial joints and gears
How are nanoparticles used in relation to electricity?
Nanotubes conduct electricity so they can be used in tiny electric circuits for computer chips
What are plastics made up of?
Lots of molecules joined together in long chains
What determines the properties of plastics?
The forces between the molecule chains
What hold the atoms together in long chains in plastics?
Strong covalent bonds
How are individual tangled chains of polymers held together?
So…
Which polymers don’t have cross links between chains?
Why is it easy to melt this type of plastic?
What happens when the polymer cools?
So what is the main good use of this type of polymer?
By weak intermolecular forces
…are free to slide over each other.
Thermosoftening polymers
The forces between the chains are easy to overcome so it’s easy to break these and melt the substance
It hardens into a new shape
They can be melted and remoulded as many times as needed
How are some chains of polymers held together?
What type of polymers have these…. ?
How is the structure held?
What happens when the polymer is heated?
So what are the properties of this type of polymer?
Some have stronger intermolecular forces between the chains called cross links, these hold the chains firmly together Thermosetting polymers have cross links In a solid structure It doesn't soften They are hard, strong and rigid
What affects the properties of a polymer? (2)
The starting materials and the reaction conditions
How is low density polythene made? (two conditions)
What can it now be used for due to what property?
Heat ethene to about 200 degrees, under high pressure
It’s flexible and so can be used for bags and bottles
How is high density polythene made? (two conditions)
What can it now be used for due to what property?
Lower temperature and pressure with a catalyst
It’s rigid and so can be used for water tanks and drain pipes
What plastic would you use for the following and why?: (softening or setting)
- Clothes
- Disposable cups
- Measuring cylinder
1 thermosoftening because it must be flexible
2 thermosetting because the cup mustn’t melt
2 thermosetting because the tube must be rigid
What are nanoparticles? (2 options, or list a property) Exam question, 1 mark
Particles 1-100nm in size
Particles with different properties to normal particles of the same substance
