‘First’ recyclable thermoset plastics produced

A close up of the new polymers (Picture credit: IBM)

Researchers at IBM Almaden Research Center have created the ‘first’ thermoset plastics that are completely recyclable.

The Californian scientists have successfully demonstrated (see video) a new class of polymer that is ‘resistant to cracking, stronger than bone, can reform to its original shape (self-heal), and completely recyclable’.

First reported in the journal Science by a research team involving IBM’s Almaden Research Laboratory in San Jose, the new family of polymers (which has not yet been named) includes a strong, stiff plastic and a stretchy gel that can fix itself when torn.

The polymers were reportedly discovered by accident, after one of the scientists left one of three components out of a reaction. Specifically, and in highly scientific terms, the process involves ‘paraformaldehyde and 4,4ʹ-oxydianiline (ODA) forming hemiaminal dynamic covalent networks (HDCNs), which can further cyclize at high temperatures, producing poly(hexahydrotriazine)s (PHTs)’.

The researcher responsible for discovering the new polymers, Dr Jeanette Garcia, found the resulting material to be so strong that she had to smash the beaker containing the material with a hammer to access it.

The polymers are reportedly the ‘first’ thermoset plastics that can be recycled, as traditional thermoset plastics (such as Bakelite) cannot be reworked once cured.

Once fully submerged in sulphuric acid (and left to soak), the polymer completely breaks down into its original material, which can then be repolymerised for reuse.

Although yet to be developed for commercial purposes, it is hoped the new polymer could ‘transform manufacturing and fabrication in the fields of transportation, aerospace, and microelectronics’ as not only is the material flexible and self-healing, but can also be made as much as 50 per cent stronger when blended in composite form with carbon nanotubes.

‘It’s such a simple reaction’

Speaking of the discovery, Garcia told the BBC: “I had this chunk of plastic, and I had to figure out what it was. I had to smash my round-bottomed flask with a hammer.

"It was definitely fortuitous, the first thing I did, of course, was to hit the literature, to try and see if it'd been done before. I just assumed that it had been – it's such a simple reaction."

James Hedrick, Advanced Organic Materials Scientist at IBM, who was in charge of the research, added: “Although there has been significant work in high-performance materials, today’s engineered polymers still lack several fundamental attributes. New materials innovation is critical to addressing major global challenges, developing new products and emerging disruptive technologies  

“We’re now able to predict how molecules will respond to chemical reactions and build new polymer structures with significant guidance from computation that facilitates accelerated materials discovery. This is unique to IBM and allows us to address the complex needs of advanced materials for applications in transportation, microelectronic or advanced manufacturing.”

His Highness Prince Turki bin Saud, Vice President of Research Institutes King Abdulaziz City for Science and Technology (KACST), which was also involved in the research, added: “By joining forces with IBM Research and bringing together the minds of KACST and IBM scientists, we have managed to merge the strengths of both sides, making it possible to bring forth novel green materials that exhibit excellent properties while being completely recyclable. We believe that this work can have significant impact to multiple industries and hope to see more great things come from our collaboration.” 

‘Ninja polymers’

This is the second such breakthrough IBM Research has claimed, after its scientists recently also transformed used plastic into polymers that can fight suberbugs, including drug-resistant killers like methicillin-resistant Staphylococcus aureus (MRSA), involved in 0.2 per cent of all UK hospital deaths between 2008 and 2012.

The team converted polyethylene terephthalate (PET) from waste plastic bottles into ‘biocompatible’ materials that specifically target and attack bacterial and fungal infections but these ‘ninja polymers’, as the team is calling them, differ from traditional antibiotics to which some bacteria develop resistance. 

Read more about IBM Research’s ninja polymers or its recent discovery of a new recyclable polymer.