Smart Materials

Question 1

Shape memory alloy (SMA) - Nitinol

Answer 1

SMA wire also called ‘Nitinol’ as it is a composed of nickel and titanium. Looks like ordinary wire and has many of the same properties.
SMA has a memory - for example if it is folded to form a shape and then heated above 90 degrees centigrade it returns to its original shape

Question 2

Shape memory alloy (SMA) - electrical currents

Answer 2

SMA can be programmed to remember a shape. Clamp the SMA in posterior and pass an electric current though it. If the wire is now folded into another shape and then placed in hot water, it returns to the original ‘programmed’ shape

Question 3

Thermochromic inks

Answer 3

Thermochromic inks change colour in response to changes in temperature. These inks have serious applications such as in the food industry. They can be used to indicate when a packaged food has reached the correct temperature in an oven. They are also used in forehead thermometers

Question 4

Hydrochromic inks

Answer 4

Hydrochromic inks are those that change colour when they make contact with colour.
E.g. - a plastic moisture tester is punched into the soil alongside the plant.
If the water content of the soil is at the right level, the colour of the moisture tester should remain blue.
However if the soil becomes dry, the colour changes to yellow.

Question 5

Photochromic inks

Answer 5

Photochromic ink darkens, as the light level increases. Some photochromic inks change colour. In fact, it is UV light that causes the darkening of the ink, which means the ink works best in natural light. This special ink has two main applications: sunglasses and spectacles

Question 6

Aroma pigments - “scratch and sniff”

Answer 6

These are inks/paints that produce an aroma when scratched. They are popular in ‘scratch and sniff’ products, such as perfume samples etched into woman’s magazines. The reader scratches the sample aroma pigment, releasing and aroma matching the selected perfume

Question 7

Encapsulating polymers

Answer 7

Polymers that absorb oil, forming a rubbery substance. They are environmentally ‘friendly’, developed to manage hydrocarbon-based liquid spills.
A potential practical application is at petrol/diesel fuel stations. If a spill at the pump takes place, a HC polymer can be applied, absorbing the fuel, safely. It can then be used as a solid fuel and even burned

Question 8

Polymorph

Answer 8

Polymorph is a thermoplastic material that can be shaped and reshaped any number of times.
Supplied as granules. Heated in hot water at 62 degrees centigrade, the granules form a mass of ‘clear’ material that can be shaped into almost any form. On cooling it becomes a solid.
Suitable for 3D modelling, as it can be shaped by hand or pressed into a shape though the use of a mould

Question 9

Electrochromic

Answer 9

Changes colour according to varying electrical input

Question 10

Phosphorescent

Answer 10

Inks are able to absorb light during the day and then glow at night
E.g. A fire exit design

Question 11

Define smart material

Answer 11

Materials that interact with their environment and return to their original state once the stimulus is removed
E.g. Light or heat

Question 12

Briefly describe what smart materials are

Answer 12

Smart materials can change their properties in response to an external stimulus

Question 13

Suggest and describe a smart material

Answer 13

An example is thermochromic materials that change colour depending on their temperature.
Thermochromic ink that changes colour when the microchip gets too hot

Question 14

Describe the potential environmental benefit of using potatopak

Answer 14

It’s biodegradable

Question 15

What does PMC stand for

Answer 15

Precious metal clays