Modern and smart materials

The differences between smart, modern and composite materials

What is a modern material?

Modern materials are not naturally occurring, and have to have been developed. Modern materials are used alongside traditional materials such as paper, wood, stone and metals.

A modern material is a material that has been engineered to have improved properties.

What is a smart material?

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

To be classed as a ‘smart material’ they need to exhibit a physical change in response to some external stimuli.

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.

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.

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.

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.

A close-up image of water droplets on a dark waterproof fabric.
Hydrophobic material

Photochromic 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.

Reactive glass is a material that changes from transparent to opaque by passing current through an electrochromic material built into the glass. Common applications include privacy glass and auto-dimming rear view mirrors in cars that help prevent the driver being dazzled by bright lights.

An auto-dimming rear view mirror in a car is shown as an example of reactive glass.
Reactive glass used in an auto-dimming rear view mirror in a car

A piezoelectric material can generate electricity when pressure is applied. Common applications include keypad sensors, alarm systems and microphones. Quartz crystals are an example of a piezoelectric material.

Conductive inks are made from a precious metal, such as silver, which can make them expensive. They are available in pen form and can be used to draw circuit diagrams. When the ink dries a current is able to flow through the material.

Temperature-responsive polymers respond to temperature change by displaying a change in property. This is a new material and is still under research but current applications are in the medical field for the controlled delivery of medication.