"Trash into treasure": Carolina chemists make recycled plastics stronger

A group of chemists at the University of North Carolina (UNC) at Chapel Hill claim to have developed a way to break down plastic waste and turn it into stronger and more valuable products.

By modifying the carbon-hydrogen bond that is present in thermoplastics - the building blocks for bottles, plastic bags and children's toys - the team could extend the lifespan of plastics beyond single-use.

Read more: The £1.8m challenge to tackle plastic waste in Sub-Saharan Africa

The US generates more plastic waste than any other nation, but only recycles around 9% of its trash. Combatting mounting plastic waste and the threats it poses both to the environment and animal life has become one of the hot topics of our day.

Thermoplastics typically weaken with reuse as they are heated down to their base components which means there is little profit incentive to reusing. This leads to waste being dumped into landfills or clogging the world's oceans.

“Our approach views plastic waste as a potentially valuable resource for the production of new molecules and materials,” said Frank Leibfarth, assistant professor of chemistry in the UNC College of Arts & Sciences. 

“We hope this method could drive an economic incentive to recycle plastic, literally turning trash into treasure".

The two lead scientists in charge of this research describe their breakthrough as "closing the loop" on plastic recycling - a move that could bring this problematic manufacturing sector in line with a circular economy.

The process involves stripping hydrogen atoms from the polymer and then creating new compounds that would previously have been considered chemically inert, meaning no reaction would take place.

“The versatility of our approach is that it enables many valuable transformations of carbon-hydrogen bonds on such a wide range of important compounds,” UNC-Chapel Hill professor Erik Alexanian said.

Liebfarth's group is concerned with creating polymers that are both stronger and more sustainable and has been researching into methods for this kind of plastics reuse for several years. Back in 2020, his team reportedly developed a plastic bottle that removes harmful chemicals from drinking water - which has become a real issue in the US.

In particular, the team want to target polymers that are more difficult to recycle and give them a new lease of life. Their first major project was on the packaging foam typically used to transport electronics products.

The process is particularly useful as much recycled plastic waste is often downturned into polyester clothing or carpets. This often finds its way into the world's oceans.

"If the chemistry can be repeatedly applied to polymers to help recycle them over and over again, it could change the way we look at plastic", Liebfarth added.

The North Pacific Ocean is currently home to a giant garbage patch trapped in a vortex that poses a massive danger to local marine ecosystems.

Once in the ocean, the plastic is notoriously difficult to remove and recycle. Plastic waste that ends up in landfills is often incinerated, which can release toxic gases and add to the greenhouse effect.

The coronavirus pandemic has only exacerbated the issue of plastic pollution, with an estimated 8.4 million tonnes being generated through disposable products such as face masks. This has led to separate schemes in a bid to tackle this issue before it gets too out of hand.

Some researchers have also looked to kill two birds with one stone and hope to turn plastic waste into hydrogen for use in the energy sector.

Read more: Peel NRE announced plans for waste plastic to hydrogen facility in Scotland

Some economies, such as New Zealand and the EU, have vowed to ban single-use plastics. Should these bans be instigated more commonly, their reuse through processes such as those discovered by UNC could circumvent this ban while also offering durable, sustainable plastics for public use.

Turning them into completely different products could also offer a valuable new resource for packaging or consumer goods.

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