This Material Heals Under Pressure Rather than Cracking

A Japanese team of researchers created a new polymer that can repair itself under extensive pressure.

This Material Heals Under Pressure Rather than Cracking
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A team of materials engineers from Japan developed a new type of glass that can "heal itself" when put under pressure rather than crack. The new glass could give objects like cell phone screens the ability to 'pull' itself back together after experiencing extensive damage. 

The glass is made from a polymer dubbed the "polyether-thioureas." It heals itself when pressed together by hands without the need for melting and molding the material. 

The research can be found in the latest edition of Science magazine and journal. 

"The hydrogen bonds form in a such a way that the polymer doesn't crystallize, giving the molecular chains the ability to move freely, and easily combine when pieces of the substance are compressed," Science noted about the research coming from Tokyo. 

During testing, the glass was cut and then gently compressed for 30 seconds. The team then discovered that a 2-square-centimeter sheet of the newly 'melded' material could hold the same weight as a full can of soda -- approximately 300 grams. 

"High mechanical robustness and healing ability tend to be mutually exclusive," said researchers. "In most cases, heating to high temperatures, on the order of 120 degrees Celsius or more, to reorganize their cross-linked networks is necessary for the fractured portions to repair."

This Material Heals Under Pressure Rather than Cracking
Source: Wang Lab via Science Daily

One of the best parts of these new findings is that the discovery was serendipitous. Graduate school student Yu Yanagisawa was attempting to make a glue. The polymer was intended to be a very strong adhesive, but through trial and error, he found that the polymer could adhere to itself again with just being manually compressed. 

"I hope the repairable glass becomes a new environment-friendly material that avoids the need to be thrown away if broken," said Yanagisawa in an interview with NHK News Web. 

If this research continues and the polymer gets cleared to scale up for production, smartphone users having broken or shattered screens could become a thing of the past. 

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Other Self-Healing Materials

The discovery from Tokyo joins other previous forays into developing "self-healing" materials. 

In April 2017, researchers from the University of California created an X-Men/Wolverine inspired material. The team used an ion-dipole interaction and a polar, stretchable polymer with an ionic salt. They then improved the properties, enhancing the attractive properties of both.

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"When I was young, my idol was Wolverine from the X-Men," Chao Wang, Ph.D., said in a press release. "He could save the world, but only because he could heal himself. A self-healing material, when carved into two parts, can go back together like nothing has happened, just like our human skin. I've been researching making a self-healing lithium ion battery, so when you drop your cell phone, it could fix itself and last much longer." 

Before the latest research, smartphone companies were already looking to leverage self-healing technology. The LG G Flex 2 took the most notable attempt at it in 2015. The Guardian took a full report of the self-healing coating on the back of the phone: 

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"The back is covered in a self-healing coating, that seals up and removes small scratches within around 15 minutes. In testing a slightly heavier scratch couldn’t be healed, but over the space of about 20 minutes it did diminish in visibility but could still be felt. The G Flex 2 is more average-Joe-on-the-street than Wolverine powers of healing."

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