After decades of research, experts have discovered the first ever “auxetic” synthetic material that becomes thicker when it is stretched.
The new non-porous material has unique stretching properties which enable it to, when pulled, become thicker perpendicular to the applied force, this known as ‘auxetics’.
There are materials in nature that exhibit auxetic capabilities, such as cat skin, the protective layer in mussel shells and tendons in the human body.
Experts have been researching synthetic auxetic materials for years, but until now have only been able to create them by altering conventional materials using complex processes. This often time-consuming, costly, and can lead to weaker, porous products.
The identification of a synthetic molecular version is a major step forward for material science. However, more research is needed to develop a fuller understanding of what drives this unique behaviour.
The innovation could have significant benefits in the development of products with a wide range of applications. Auxetics materials also have a high energy absorption and resisting fracture. This means there may be many potential uses for the synthetic structure, including body armour, architecture and medical equipment.
The team at Leeds University discovered the material while examining the capabilities of liquid crystal elastomers. Liquid crystals are best known for their use in mobile phone and television screens and have both liquid and solid properties.
When these liquid crystals are linked with polymer chains to form rubbery networks, the material becomes auxetic at a molecular level. This gives it a entirely new set of properties.
The importance of material science
Material science aims to find the most appropriate materials for structures, products and devices. Whether products need to be lighter, more durable or water-resistant for various reasons, material science plays a vital role in finding these options.
That role looks set to continue, as government policy and awareness of the environment became important factors in manufacturing, consumer buying habits and material understanding.
For example, plastic for its properties is an outstanding material, it is light, cheap and durable. However, plastic waste has become a enormous issue of our time, and over eight million tonnes of it seeps into the oceans each year. Is it no longer an appropriate material?
Single use plastics are everywhere, straws, water bottles, coffee cups and these often head straight to landfill, to be incinerated or in the worst case, end up polluting the environment after use. Now consumers and manufacturers are radically changing their strategies to choose a more sustainable option, like producing and using reusable cups and paper straws.
There are many more examples of materials which were once championed, fuels for example, that are now slowly being phased out. This is particularly difficult for manufacturers who have to deal with this disruption to their process which may have been operating for decades. Material science can help to aid in this period of change.