New shape-shifting material made with ingredients found in diapers tougher than cartilage

 By Tom Campbell via SWNS

A new shape-shifting material made with ingredients found in contact lenses and diapers is tougher than cartilage, according to a new study.

The substance, which is both extremely strong and stretchy, returns to its original shape after being deformed when exposed to heat, say scientists.

While many natural materials like cartilage have the benefit of being tough and stretchy, reproducing them has proved difficult.

But now researchers at North Carolina State University in the US have come with a solution which is easy to produce and can be used for 3D-printing. ​

Co-author Professor Michael Dickey said: "Materials that can be deformed, but that are difficult to break or tear, are desirable.

"Nature is good at this; think of cartilage as an example.

"But engineering synthetic materials with these properties has been difficult, which makes our work here exciting.”

The researchers used two materials - polyacrylamide and polyacrylic, which are respectively used to make contact lenses and diapers.

These were combined by placing them in an ionic liquid and shinning an ultra violet light through them.

Professor Dickey said: "The end result is significantly better than an average of the two materials.

"It is like adding 1+1 and getting 10.

"The resulting gel has the stretchability of polyacrylic acid and is even stronger than the polyacrylamide."

The new material, known as an ionogel, contains salts which are liquid at room temperature, unlike hydrogels for example which are made with water.

Professor Dickey said: "Hydrogels, which are polymer networks that contain water, are fairly common."

The new gel has self-healing and shape memory properties, meaning a deformed piece will return to its original shape when exposed to heat.

Two pieces which have been stuck together will also reform a stronger bond when the temperature is increased.

Professor Dickey said: "In terms of toughness, it’s better than cartilage.

"But the differences between ionogels and hydrogels make them advantageous for different applications.”

This will occur in a matter of seconds at a temperature of 60 degrees Celsius, and will be faster the hotter it gets.

Professor Dickey said: "We’re excited that we’ve made something with truly remarkable properties that can be made very easily – you just shine light on it – using widely available polymers.

"And you can tailor the properties of the ionogels by controlling the ratio of ingredients during the copolymerisation process."

The researchers are now exploring how their new discovery can be used in different industries.

Professor Dickey said: "We’re already working with one industry partner, and are open to working with others to develop applications for this new breed of ionogels.”

The findings were published in the journal Nature Materials.