How cool is it to watch Wolverine beat the hell out of bad guys even after being riddled with bullets? Wolverine’s superpower – his healing factor is what makes him the coolest of X-Men superheroes. But wait, our favourite superhero with metal claws had a phone in his pocket and its screen got cracked in the hubris. What if his phone too could heal, just like him?
Most of the flagship phones that sell these days have glass bodies. Glass allows for stronger Bluetooth, Wi-Fi and LTE signals while giving that premium look and feel that customers seek. However, glass being a brittle material is prone to cracks on impact. And unlike the virtually unbreakable Nokia 3310, a shattered phone is not very uncommon.
Wolverine and his abilities are fiction, but what this budding scientist has created something which is not; a self healing material which can heal itself as fast. A self-professed fanboy of Wolverine, researcher Chao Wang said in a press release from the American Chemical Society, “When I was young, my idol was Wolverine from the X-Men.. He could save the world, but only because he could heal himself”. Wang began working on a material that could stitch itself back together after damage, and came up with the game-changing polymer.
What’s the secret of the superpower?
Chemical bonding is the key to self-repair. Two-types of bonds exist in materials, explains Wang – covalent bonds, which are strong and don’t readily reform once broken; and non-covalent bonds, which are weaker and more dynamic. Take for example, the hydrogen bonds that connect water molecules to one another are non-covalent, which can break and re-form constantly to give rise to the fluid properties of water. “Most self-healing polymers form hydrogen bonds or metal-ligand coordination, but these are not suitable for ionic conductors,” Wang says.
So Wang’s team at the University of California, Riverside resorted to a different type of non-covalent bond called and ion-dipole interaction, a force between charged ions and polar molecules. According to Wang, “Ion-dipole interactions have never been used for designing self-healing polymer, but it turns out that they are particularly suitable for ionic conductors.” The key design idea in the development of the material was to use a polar, stretchable polymer, poly(vinylidene fluoride-co-hexafluoropropylene), with a mobile, ionic salt. The polymer chains are linked to each other by ion-dipole interactions between the polar groups in the polymer and the ionic salt.
You can watch this video to understand how a ion-dipole interaction works.
The material this resulted in could stretch upto 50 times its usual size. It even stitched itself back within 24 hours automatically after being torn in two.
Smartphone with healing factor
Wang explains in a press conference on the topic that if we make smartphones with this new material, they would be able to repair the phone’s screen and even the battery. Within just 48 hours the material would be able to recover all of its properties including conductivity and stretchability. He also emphasised the relatively low cost of the material.
What’s the future?
The researches generated an “artificial muscle” as a test, by placing a non-conductive membrane between two layers of the ionic conductor. The new material was found to respond to electric signals, bringing motion to this artificial muscles. This is much akin to how biological muscles move in response to electrical signals. Despite its potential uses, Wang’s materials are not intended for medical applications for now.
The researchers are working on altering the polymer to improve the material’s properties. For instance, they are testing the material in harsh conditions, such as high humidity. Wang says, “Previous self-healing polymers haven’t worked well in high humidity. Water gets in there and messes things up. It can change the mechanical properties. We are currently tweaking the covalent bonds within the polymer itself to get these materials ready for real-world applications.”
Wang believes, the self-healing material will be use for phone screens and batteries as early as 2020. “Within three years, more self-healing products will go to market and change our everyday life. It will make our cellphones achieve much better performance than what they can achieve right now,” he explains.
Good news for those who have ‘slippery hands’ as cracked screens and costly replacements will become a thing of the past.