Copyright © 2007 Dorling Kindersley
Materials scientists develop and test new materials that do certain jobs better than existing materials, or are easier or cheaper to make. Scientists use their knowledge of how molecules form to combine atoms in new ways. They also apply heat and pressure to existing materials to create materials with new properties. They can even create materials with SMART properties that respond to their environment.
In freezing conditions, climbers need clothes that are extremely warm and lightweight, so they can move easily. Aerogel is a new, super-light insulating material used to line extreme weather coats. It is made from silicon dioxide, the same material that glass is made from. However, aerogel is 99 per cent air, so it is 1,000 times less dense than glass.
One of the lightest substances on Earth, aerogel can even float on air in its pure form. It also has amazing insulation properties and can protect skin from the heat of a blowtorch. Aerogel is made by mixing a silicon compound with other chemicals to make a wet gel. The gel is dried at a high temperature and pressure.
NASA has used cells of aerogel on a spacecraft called Stardust to collect dust from a comet called Wild 2. The comet dust collector contains rectangular cells, which are lined with aerogel.
The panels of aerogel cells are placed into position on Stardust. The spongy texture of aerogel means that comet dust particles travelling at six times the speed of a bullet can be slowed down and captured without being squashed or altered.
Stardust reached Comet Wild 2 in January 2004. The dust collector has trapped grains of comet dust the size of a grain of sand. By studying the particles, scientists hope to learn more about comets and the early Solar System.
This prototype computer is made from a fabric that conducts electricity. The fabric, called ElekTex™, contains fibres that have a thin coating of silver or copper – these metals are good electrical conductors. Microchips woven into the fabric translate the electrical impulses from the fibres into digital data, which can be viewed on the computer’s screen.
Prototype mobile phones made from ElekTex™ are lightweight and water-resistant. They can also be folded up and crumpled without breaking. These properties make them a lot more hard-wearing than traditional mobile phones.
A smart material senses a change to its environment and responds by altering in some way. Each type of smart material has a different property that changes, such as stiffness, colour, shape, or conductivity (ability to conduct electricity). For instance, a piezoelectric material gives off a small electric current when bent, and is used in car passenger airbags. If the car slows down suddenly, the piezoelectric bends and sends out an electric charge, which blows up the airbag.
Self-healing plastics could provide a breakthrough in surgery. If an artificial bone joint such as a metal hip wears out, it is difficult to replace it. However, a joint made of self-healing plastic would be able to repair itself, just like a bone can. If the artificial joint cracked, it could be almost good as new again within a few days.
Plastic is made of thousands of small molecules called monomers linked together to form polymers. A new, self-healing plastic contains tiny capsules filled with liquid monomer. If the plastic cracks, the capsules burst and release the liquid into the crack. A black catalyst in the plastic makes the liquid monomer molecules link up to create polymers and form new plastic that repairs the break.