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Strong, lightweight polymers are also recyclable and self-healing

Most of us have grown accustomed to tossing a pop bottle or product packaging in the recycling. But as soon as a plastic needs to survive a harsher environment–think airplane wings and the innards of mobile phones–the plastic used is likely what is known as a thermoset. Thermosets are made at a very high temperature and, once set, their chemical composition changes and their form is irreversible. This means they can’t be recycled.

IBM researchers have created the first thermosets that shares the strength and light weight of its earlier cousins while also being recyclable. Detailed in Science (subscription required) today, the materials are also self-healing and less likely to crack. They make up a totally new family of polymers–the first in decades. While the first of the two polymers was stumbled upon by accident, the second was developed by prompting a computer to model a range of variants.

A close-up view of one of the polymers. Photo courtesy of IBM.
A close-up view of one of the polymers. Photo courtesy of IBM.

Unlike everyday plastics that are generally recycled by being exposed to heat and melted down, IBM’s materials are returned to their original state by being exposed to acid. And their ability to self-heal means it is also less likely they need to be recycled in the first place. If a crack forms, the two sides just need to be placed so that they touch each other and the polymer will naturally heal back together.

The materials could be useful in electronics manufacturing facilities, where currently when there is an error adding a thermoset, the entire chip needs to be thrown away. But Timothy Long of the Virginia Tech department of chemistry wrote in Science (subscription required) today that they could also lead to better recycling for used electronics, not to mention packaging and aerospace or automotive parts.

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