Developments in new materials - OCRSmart, modern and composite materials

Traditional materials are those that have been in use for centuries, such as paper, wood, stone and metals. Further materials have been developed, such as modern materials and smart materials, which can be used alongside the traditional materials. Modern and smart materials are constantly being engineered, so it’s good to try to keep up to date with the latest developments. They can often be incorporated into new consumer products without people noticing.

Modern materials

Concrete, aluminium and steel are all commonly used modern materials, but more-recent additions include materials that have changed the way we manufacture and use products.

Graphene is a single carbon layer material which is hypothetically 100 times stronger than steel. It is hypothetical because we are yet to manufacture it in large enough quantities to prove this. In theory, it could provide body armour that is bulletproof, invisible and almost weightless.

If you covered the whole of Wembley Stadium in a layer of graphene, it would be almost invisible and be unbreakable, yet you would be able to lift it all with one finger.

Titanium is a modern metal and is used in sporting and medical applications, such as replacement hip joints and high-performance bicycles. It is an excellent material for these purposes as it has a high strength-to-weight ratio and is resistant to corrosion.

Metal foams are a strong but lightweight modern material produced by injecting a gas or foaming agent into molten metal. Typically, only 5-25 per cent of the foam is the metal, and this allows the material to retain much of its strength but without the density or weight of a solid metal. Metal foams are often used in vehicles such as planes and cars as they absorb shock effectively if the vehicle crashes.

Liquid crystal displays (LCDs) use the light-modulating properties of liquid crystals to display an image. The liquid crystals are between a liquid and solid state. When charge is applied to each liquid crystal, the shape changes to either block light or let light through. This ensures text or images display on the LCD.

LCDs require a backlight to work and many modern devices now use Organic Light Emitting Diodes (OLEDs) instead, which allows devices to be thinner and lighter. OLEDs are more expensive as each pixel is its own light, but they allow for thinner panels and better colour and contrast.

Superalloys are a modern material and are typically used in modern aircraft where specific extreme properties are needed. As planes are put under extreme pressure forces and exposed to high levels of heat in the engines, they need to use materials that have excellent strength and heat resistance. The superalloys used are typically nickel, iron-nickel or cobalt alloys.

Nanomaterials are tiny particles of 1 to 100 nanometres (nm) that can be used in thin films or coatings such as the oleophobic coatings on smartphone screens that repel greasy fingerprints, or hydrophobic materials that repel water.

Smart materials

While smart materials are modern materials, modern materials are not necessarily smart.

In other words, they change when you do something to them, and when you remove what is causing that change, they return to their original form.

Shape-memory alloys (SMA) are metal alloys that can remember their shape when heated. These alloys have been utilised on spectacle frames that spring back to shape if they are squashed.

Nickel titanium (nitinol) is a type of SMA, and it contracts when heated, whereas most metals expand. When braces are made from nitinol, they heat up in the mouth and ‘pull’ on the teeth, so they move with the nitinol.

Thermochromic pigments change colour when their temperature changes. The term ‘thermo’ relates to heat, and chroma means colour - so thermochromic pigments change colour when they are heated up. These pigments can be mixed with paint or polymers to give the materials the same colour-changing properties as the pigment. You may have seen this technology on colour-changing mugs or bath items for children.

Photochromic pigments work in a similar way but 'photo' refers to light - so these pigments change their properties when exposed to ultraviolet (UV) light. A well-known example would be glasses where the lenses are clear when worn inside a building, but become more like sunglasses when exposed to bright sunlight outside. The same technology has been used in windows to prevent rooms from getting too hot in warm weather.

Quantum-tunnelling composite (QTC) is an insulating rubber containing tiny particles of metal. When squashed, the metal particles meet and allow the flow of electrical current. As a result, QTC is an insulator when resting and a conductor when pressure is applied. It is often used in outdoor applications where water might otherwise damage tiny microswitches. It has been used in clothing to control smartphones and portable music players, in power tools to give variable speed controls and in touch-sensitive pads.

Self-healing materials have the ability to repair themselves, which can extend the lifespan of the products that use them. These include polymers that can heal knife cuts in themselves, metals that resist corrosion and concrete that can heal when cracked.

Ferrofluids can be formed by a magnetic field and are being used in hydraulic suspension pistons, with the strength of the magnetic field allowing the suspension to be hard or soft depending on what is necessary. They also have friction reducing properties allowing magnetic objects to glide across the surface.

Polymorph is a polymer that becomes malleable when heated to about 62°C. When it cools down it becomes hard enough to drill and cut. This makes it perfect for modelling as it can be reheated and formed again. It is also excellent for creating ergonomic handles and models.

Biopolymers

These are polymers that are produced by living organisms. As a natural resource, biopolymers are biodegradable and will naturally compost. Biopolymers can come from starch, sugar, cellulose or synthetic materials.

Biopolymers are seen as beneficial to the environment as they are a sustainable natural resource that naturally decompose and do not produce carbon emissions.